Ibaraki, Japan

National Institute for Materials Science is an Independent Administrative Institution and one of the largest scientific research centers in Japan. Wikipedia.


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The present invention relates to an organic/heterometallic hybrid polymer including a plurality of organic metal complexes and a plurality of transition metals, the organic/heterometallic hybrid polymer, wherein the plurality of organic metal complexes are linked in a linear manner by sandwiching each of the plurality of transition metals therebetween, the organic metal complexes include two ligands each having a terpyridyl group and one connector having Ru(dppe)_(2 )and two ethynylene groups, and the two ligands are linked by the connector, so that a nitrogen atom at position 1 of the terpyridyl group is directed toward the terminal side of the molecule of the organic metal complex, and the terpyridyl groups of at least two different organic metal complexes of the plurality of organic metal complexes are bound to one of the transition metals through a coordinate bond, thereby linking the plurality of organic metal complexes while sandwiching the plurality of transition metals alternately therebetween.


Patent
Japan National Institute of Materials Science | Date: 2016-12-08

Disclosed herein is a nickel-based heat-resistant superalloy produced by a casting and forging method, the nickel-based heat-resistant superalloy comprising 2.0 mass % or more but 25 mass % or less of chromium, 0.2 mass % or more but 7.0 mass % or less of aluminum, 19.5 mass % or more but 55.0 mass % or less of cobalt, [0.17(mass % of cobalt content23)+3] mass % or more but [0.17(mass % of cobalt content20)+7] mass % or less and 5.1 mass % or more of titanium, and the balance being nickel and inevitable impurities, and being subjected to solution heat treatment at 93% or more but less than 100% of a solvus temperature.


Patent
Japan National Institute of Materials Science | Date: 2014-11-21

Provided are an oxynitride phosphor comprising a JEM crystal as a main component and being characterized by light-emitting properties (light emission color or excitation property, light emission spectrum) that is different from the known JEM phosphor, and an application thereof. The phosphor of the present invention comprises the JEM crystal activated with Eu and represented by MAl(Si, Al)_(6)(O, N)_(10 )(where the M element is one or more elements selected from the group consisting of Ca, Sr, Eu, La, Sc, Y, and lanthanoid elements; and includes at least Eu as well as Ca and/or Sr).


Patent
Japan National Institute of Materials Science | Date: 2016-10-31

The CPPGMR element of the present invention has an orientation layer 12 formed on a substrate 11 to texture a Heusler alloy into a (100) direction, an underlying layer 13 that is an electrode for magneto-resistance measurement stacked on the orientation layer 12, a lower ferromagnetic layer 14 and an upper ferromagnetic layer 16 each stacked on the underlying layer 13 and made of a Heusler alloy, a spacer layer 15 sandwiched between the lower ferromagnetic layers 14 and the upper ferromagnetic layers 16, and a cap layer 17 stacked on the upper ferromagnetic layer 16 for surface-protection. This manner makes it possible to provide, inexpensively, an element using a current-perpendicular-to-plane giant magneto-resistance effect (CPPGMR) of a thin film having a trilayered structure of a ferromagnetic metal/a nonmagnetic metal/a ferromagnetic metal, thereby showing excellent performances.


Patent
Sharp Kabushiki Kaisha and Japan National Institute of Materials Science | Date: 2016-08-15

The present invention provides a light emitting device that makes it possible to provide an image display apparatus having a wide color reproduction range. The light emitting device includes a light emitting element that emits blue light; a Mn^(2+)-activated -AlON phosphor that is a green phosphor; and a Mn^(4+)-activated phosphor that is a red phosphor. The green light emitted by the Mn^(2+)-activated -AlON phosphor has an emission-spectrum peak wavelength of not less than 518 nm and not more than 528 nm.


Patent
Japan National Institute of Materials Science | Date: 2015-05-14

By using silicon oxynitride with an oxygen content of 4.2 to 37.5 at % as a material for a barrier layer, adhesiveness similar to that of silicon oxide and an Ag diffusion prevention property similar to that of silicon nitride can be realized. In particular, in a semiconductor device in which a plurality of silicon chips is vertically stacked by through-silicon vias, Ag is prevented from being diffused into Si and adhesiveness to Si becomes favorable when an Ag/polypyrrole complex is used as a conductive filling material used for the formation of a barrier layer provided on the inner surface of the via.


The present invention relates to an organic/heterometallic hybrid polymer including a plurality of organic metal complexes and a plurality of transition metals, the organic/heterometallic hybrid polymer, whereinthe plurality of organic metal complexes are linked in a linear manner by sandwiching each of the plurality of transition metals therebetween,the organic metal complexes include two ligands each having a terpyridyl group and one connector having Ru(dppe)_(2) and two ethynylene groups, and the two ligands are linked by the connector, so that a nitrogen atom at position 1 of the terpyridyl group is directed toward the terminal side of the molecule of the organic metal complex, andthe terpyridyl groups of at least two different organic metal complexes of the plurality of organic metal complexes are bound to one of the transition metals through a coordinate bond, thereby linking the plurality of organic metal complexes while sandwiching the plurality of transition metals alternately therebetween.


As an object to provide a lithium-ion supercapacitor having a high energy density and a high power density, capable of being charged and discharged many times, and having a long product life, there is provided a lithium-ion supercapacitor using a graphene/CNT composite electrode, the lithium-ion supercapacitor including: an anode; a cathode that is arranged to be separated from the anode; and a lithium ion electrolytic solution that fills in a space between the anode and the cathode, wherein either or both of the cathode and the anode are formed by a graphene/CNT composite, and a CNT concentration in the graphene/CNT composite is 17 wt% or more and 33 wt% or less.


A nano-coating material, capable of being bonded to the surface of a metal or an alloy substrate, the nano-coating material includes a compound having, in a polymer main chain, (A) a first side chain or a terminal, each having a binding group containing a benzene ring having at least one pair of adjacent hydroxyl groups; and (B) a functional second side chain.


Patent
Japan National Institute of Materials Science | Date: 2017-03-22

By using silicon oxynitride with an oxygen content of 4.2 to 37.5 at% as a material for a barrier layer, adhesiveness similar to that of silicon oxide and an Ag diffusion prevention property similar to that of silicon nitride can be realized. In particular, in a semiconductor device in which a plurality of silicon chips is vertically stacked by through-silicon vias, Ag is prevented from being diffused into Si and adhesiveness to Si becomes favorable when an Ag/polypyrrole complex is used as a conductive filling material used for the formation of a barrier layer provided on the inner surface of the via.


Naito K.,Japan National Institute of Materials Science | Tanaka Y.,Japan National Institute of Materials Science | Yang J.-M.,University of California at Los Angeles
Carbon | Year: 2017

In this study, transverse compressive properties of high tensile strength polyacrylonitrile (PAN)-based (T1000GB), high modulus PAN-based (M60JB), high modulus pitch-based (K13D), and high ductility pitch-based (XN-05) single carbon fibers were measured using a direct compression test. The transverse compressive modulus, Ef (TC), of T1000GB, M60JB, K13D, and XN-05 single fibers corresponded to 8.94 GPa, 3.30 GPa, 1.44 GPa, and 17.49 GPa, respectively. The transverse compressive strengths, σf (TC), of T1000GB, M60JB, K13D, and XN-05 single fibers corresponded to 0.894 GPa, 0.999 GPa, 0.037 GPa, and 1.438 GPa, respectively. The results indicate that the high ductility pitch-based, the high strength PAN-based, and the high modulus PAN-based single carbon fibers possess high compressive modulus and strength. In contrast, the high modulus pitch-based single carbon fiber possess low compressive strength and modulus. Statistical distributions of transverse compressive strength were characterized. The Weibull modulus for T1000GB, M60JB, K13D, and XN-05 single fibers corresponded to 6.86, 7.57, 9.72, and 5.41, respectively. The result indicate that the structure/microstructure parameters are clearly correlated with transverse compressive properties of PAN-based and pitch-based single carbon fibers and especially with the transverse compressive modulus/strength and the Weibull modulus of transverse compressive strength. © 2017 Elsevier Ltd


Zhu Y.M.,Monash University | Bian M.Z.,Japan National Institute of Materials Science | Nie J.F.,Monash University
Acta Materialia | Year: 2016

Microstructures of a Mg-Gd solid solution single phase alloy that has been compressed at room temperature and subsequently annealed have been examined by bright-field and high-angle annular dark-field scanning transmission electron microscopy. It is found that the deformed microstructure contains many nano-sized grains. These nanograins exhibit strong texture: most of them have their 〈12-10〉 parallel to each other. A range of tilt boundaries are detected between these nanograins, and they can be produced by basal-plane tilt or prismatic-plane tilt about the 〈12-10〉 axis. Crystallographic analysis indicates that some of these tilt boundaries can be regarded as being generated by impingements of 〈12-10〉 co-zone variants of (101-1),(101-2) and (101-3) primary twins or secondary or tertiary twins. Segregation of Gd atoms occurs in the tilt boundaries after annealing of the cold deformed sample. The larger size Gd atoms segregate preferentially to dilated atomic sites within, or adjacent to, each tilt boundary to reduce local elastic strain. Consequently, the segregated Gd atoms form a range of unique, chemically ordered patterns specific to tilt boundaries. © 2016 Acta Materialia Inc.


Nishimura T.,Japan National Institute of Materials Science
Materials | Year: 2017

Abstract: Exposure tests were performed on low alloy steels in high Cl- and high SOx environment, and the structure of the rust were analyzed by TEM (Transmission Electron Microscopy) and Raman Spectroscopy. In the exposure test site, the concentrations of Cl- and SOx were found to be high, which caused the corrosion of the steels. The conventional weathering steel (SMA: 0.6% Cr-0.4% Cu-Fe) showed higher corrosion resistance as compared to the carbon steel (SM), and Ni bearing steel exhibited the highest one. Raman spectroscopy showed that the inner rust of Ni bearing steel was mainly composed of α-FeOOH and spinel oxides. On the other hand, SMA contained β- and γ -FeOOH in inner rust, which increased the corrosion. TEM showed that nano-scale complex iron oxides containing Ni or Cr were formed in the rust on the low alloy steels, which suppressed the corrosion of steels in high Cl- and high SOx environment. © 2017 by the authors.


Demirskyi D.,Nanyang Technological University | Vasylkiv O.,Japan National Institute of Materials Science
Journal of the European Ceramic Society | Year: 2017

Tantalum diboride – boron suboxide ceramic composites were densified by spark plasma sintering at 1900 °C. Strength and fracture toughness of these bulk composites at room temperature were 490 MPa and 4 MPa m1/2, respectively. Flexural strength of B6O–TaB2 ceramics increased up to 800 °C and remained unchanged up to 1600 °C. At 1800 °C a rapid decrease in strength down to 300 MPa was observed and was accompanied by change in fracture mechanisms suggestive of decomposition of boron suboxide grains. Fracture toughness of B6O–TaB2 composites showed a minimum at 800 °C, suggestive a relaxation of thermal stresses generated from the mismatch in coefficients of thermal expansion. Flexural strength at elevated temperatures for bulk TaB2 reference sample was also investigated. Results suggest that formation of composite provides additional strengthening/toughening as in all cases flexural strength and fracture toughness of the B6O–TaB2 ceramic composite was higher than that reported for B6O monoliths. © 2017 Elsevier Ltd


Takazawa K.,Japan National Institute of Materials Science
Chemical Physics Letters | Year: 2017

Square single crystals of perylene (α-crystals) exhibit a peculiar emission pattern when excited by a focused laser beam. Fluorescence spots are observed at the point of excitation and at four edges, with the lines connecting the excitation point and edge emissions being perpendicular to the edges irrespective of the excitation position. Two different mechanisms explaining this emission pattern have been proposed so far. Our newly designed experiment and analysis revealed that the involved mechanism features a combination of the waveguide effect and total internal reflection by crystal edges. © 2016 Elsevier B.V.


Ueta H.,Japan National Institute of Materials Science | Kurahashi M.,Japan National Institute of Materials Science
Angewandte Chemie - International Edition | Year: 2017

O2 adsorption on Pt surfaces is of great technological importance owing to its relevance to reactions for the purification of car exhaust gas and the oxygen reduction on fuel-cell electrodes. Although the O2/Pt(111) system has been investigated intensively, questions still remain concerning the origin of the low O2 sticking probability and its unusual energy dependence. We herein clarify the alignment dependence of the initial sticking probability (S0) using the single spin-rotational state-selected [(J,M)=(2,2)] O2 beam. The results indicate that, at low translational energy (E0) conditions, direct activated chemisorption occurs only when the O2 axis is nearly parallel to the surface. At high energy conditions (E0>0.5 eV), however, S0 for the parallel O2 decreases with increasing E0 while that of the perpendicular O2 increases, accounting for the nearly energy-independent O2 sticking probability determined previously by a non-state-resolved experiment. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim


Kimoto K.,Japan National Institute of Materials Science | Ishizuka K.,INC Research
Ultramicroscopy | Year: 2017

The aberrations of the objective lens should be measured and adjusted to realize high spatial resolution in scanning transmission electron microscopy (STEM). Here we report a method of measuring low-order aberrations using the Fourier transforms of Ronchigrams of an arbitrary crystal such as a specimen of interest. We have applied this technique to measure first- and second-order geometrical aberrations using typical standard specimens. Focus and twofold astigmatism are measured using two Ronchigrams obtained under different foci. Axial coma and threefold astigmatism are evaluated using the Fourier transforms of small subareas of a Ronchigram. The time dependences of focus and twofold astigmatism are examined using this technique for an aberration-corrected microscope. © 2017 Elsevier B.V.


Harada H.,Japan National Institute of Materials Science
72nd World Foundry Congress, WFC 2016 | Year: 2016

Conventionally cast (CC), directionally solidified (DS) and single crystal (SC) Ni-base superalloys are used for high temperature components, typically turbine blades and vanes that determine the thrust and thermal efficiency of jet engines and power generation gas turbines. The SC superalloys have the highest temperature capabilities; a 6th generation SC superalloy TMS-238, containing Re and Ru, exhibits world highest 1120°C temperature capability. New superalloys beyond Ni-base superalloys, such as Ir-base refractory superalloys, are also being developed as possible alternative materials in the future. © 2016, The WFO (The World Foundry Organization Ltd). All rights reserved.


Kurimura S.,Japan National Institute of Materials Science
2016 IEEE Photonics Conference, IPC 2016 | Year: 2016

Nonlinear optical materials designed for specific application have been demonstrated with using quasi-phase-matching (QPM) technology. Bandwidth extension by GVM QPM or diffused QPM achieved efficient conversion in parametric OPG/OPA. Advanced fabrication technology also extends material range to the crystals with higher damage threshold. © 2016 IEEE.


Amekura H.,Japan National Institute of Materials Science
Nanotechnology Materials and Devices Conference, NMDC 2016 - Conference Proceedings | Year: 2016

Under swift heavy ion irradiation, metal nanoparticles (NPs) embedded in silica (amorphous SiO2) show shape elongation toward the same direction parallel to the ion beam. Two candidate mechanisms, i.e., the deformation of transiently molten NPs by in-plane stress from the ion hammering and that guided by the underdense track cores, are compared and criticized. Finally, the first result of C60-ion irradiation to embedded Zn nanoparticles is briefly described. © 2016 IEEE.


Inoue J.-I.,Japan National Institute of Materials Science
Journal of the Physical Society of Japan | Year: 2017

In recent extensive studies of emergent phenomena in solid-state and cold atomic systems, alteration of the symmetry inherent to a given system by applying an external time-dependent field is a central issue. We have found that how the time reversal symmetry is broken is not solely determined by temporal aspects, but also committed to spatial symmetry of the system. This connection between spatial and temporal symmetries induces various interesting phenomena that have not yet been discussed. This work reports one of these: symmetry-protected band sticking together in an effective-energy band structure of periodically driven electron systems. Experiments that could be used to observe the effect are discussed. The findings reported herein will contribute to a deeper understanding of the underlying physics and guiding principles of Floquet engineering. ©2017 The Physical Society of Japan.


Takahashi K.,Japan National Institute of Materials Science | Takahashi K.,Hokkaido University | Tanaka Y.,Hokkaido University
Physical Review B - Condensed Matter and Materials Physics | Year: 2017

Oxide-embedded bulk iron is investigated in terms of first principles calculations and data mining. Twenty-nine oxides are embedded into a vacancy site of iron where first principles calculations are performed and the resulting calculations are stored as a data set. A prediction of the dissolution energy of oxides within iron and the bulk modulus of oxide-embedded iron is performed using machine learning. In particular, support vector machine (SVM) and linear regression (LR) are implemented where descriptors for determining the dissolution energy and bulk modulus are revealed. With trained SVM and LR, the prediction of the dissolution energy for different oxides in iron and the inverse problem - deriving the corresponding descriptor variables from a desired bulk modulus - are achieved. The physical origin behind the chosen descriptors is also revealed where manipulating each individual descriptor within a multidimensional space allows for the prediction of the dissolution energy and bulk modulus. Thus, predictions of physical phenomena are, in principle, achievable if the appropriate descriptors are determined. © 2017 American Physical Society.


Hanagata N.,Japan National Institute of Materials Science | Hanagata N.,Hokkaido University
International Journal of Nanomedicine | Year: 2017

Unmethylated cytosine-guanine dinucleotide-containing oligodeoxynucleotides (CpG ODNs), which are synthetic agonists of Toll-like receptor 9 (TLR9), activate humoral and cellular immunity and are being developed as vaccine adjuvants to prevent or treat cancers, infectious diseases, and allergies. Free CpG ODNs have been used in many clinical trials implemented to verify their effects. However, recent research has reported that self-assembled CpG ODNs, protein/peptide–CpG ODN conjugates, and nanomaterial–CpG ODN complexes demonstrate higher adjuvant effects than free CpG ODNs, owing to their improved uptake efficiency into cells expressing TLR9. Moreover, protein/peptide–CpG ODN conjugates and nanomaterial–CpG ODN complexes are able to deliver CpG ODNs and antigens (or allergens) to the same types of cells, which enables a higher degree of prophylaxis or therapeutic effect. In this review, the author describes recent trends in the research and development of CpG ODN nanomedicines containing self-assembled CpG ODNs, protein/peptide–CpG ODN conjugates, and nanomaterial–CpG ODN complexes, focusing mainly on the results of preclinical and clinical studies. © 2017 Hanagata.


Omata T.,Osaka University | Nagatani H.,Osaka University | Suzuki I.,Osaka University | Kita M.,National Institute of Technology, Toyama College | And 2 more authors.
Journal of the American Chemical Society | Year: 2014

An oxide semiconductor β-CuGaO2 with a wurtzite-derived β-NaFeO2 structure has been synthesized. Structural characterization has been carried out by Rietveld analysis using XRD and SAED, and it was shown that the lattice size is very close to that of zinc oxide. The optical absorption spectrum indicated that the band gap is 1.47 eV, which matches the band gap required to achieve the theoretical maximum conversion efficiency for a single-junction solar cell. The thermoelectromotive force indicated p-type conduction in its intrinsic state. Density functional theory calculations were performed to understand the electronic structure and optical properties of the semiconductor. These calculations indicated that β-CuGaO2 is a direct semiconductor and intense absorption of light occurs near the band edge. These properties render this new material promising as an absorber in solar cells. © 2014 American Chemical Society.


Rosalie J.M.,Japan National Institute of Materials Science | Bourgeois L.,Monash University
Acta Materialia | Year: 2012

θ′ (Al 2Cu) precipitates in Al-Cu-Ag alloys were examined using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The precipitates nucleated on dislocation loops on which assemblies of γ′ (AlAg 2) precipitates were present. These dislocation loops were enriched in silver prior to θ′ precipitation. Coherent, planar interfaces between the aluminium matrix and θ′ precipitates were decorated by a layer of silver two atomic layers in thickness. It is proposed that this layer lowers the chemical component of the Al-θ′ interfacial energy. The lateral growth of the θ′ precipitates was accompanied by the extension of this silver bilayer, resulting in the loss of silver from neighbouring γ′ precipitates and contributing to the deterioration of the γ′ precipitate assemblies. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Avsar A.,National University of Singapore | Vera-Marun I.J.,National University of Singapore | Vera-Marun I.J.,Zernike Institute for Advanced Materials | Tan J.Y.,National University of Singapore | And 4 more authors.
ACS Nano | Year: 2015

The presence of direct bandgap and high mobility in semiconductor few-layer black phosphorus offers an attractive prospect for using this material in future two-dimensional electronic devices. However, creation of barrier-free contacts which is necessary to achieve high performance in black phosphorus-based devices is challenging and currently limits their potential for applications. Here, we characterize fully encapsulated ultrathin (down to bilayer) black phosphorus field effect transistors fabricated under inert gas conditions by utilizing graphene as source-drain electrodes and boron nitride as an encapsulation layer. The observation of a linear ISD-VSD behavior with negligible temperature dependence shows that graphene electrodes lead to barrier-free contacts, solving the issue of Schottky barrier limited transport in the technologically relevant two-terminal field-effect transistor geometry. Such one-atom-thick conformal source-drain electrodes also enable the black phosphorus surface to be sealed, to avoid rapid degradation, with the inert boron nitride encapsulating layer. This architecture, generally applicable for other sensitive two-dimensional crystals, results in air-stable, hysteresis-free transport characteristics. © 2015 American Chemical Society.


Zhao Y.,Beijing Normal University | Li J.-G.,Japan National Institute of Materials Science | Guo M.,Beijing Normal University | Yang X.,Beijing Normal University
Journal of Materials Chemistry C | Year: 2013

Rare-earth phosphors with tunable optical properties are used in display panels and fluorescent lamps and have potential applications in lasers and bioimaging. This work reported the preparation, structure and photoluminescence of the unilamellar nanosheets containing Tb3+/Eu3+ delaminated from layered rare-earth hydroxides (LRHs). Highly crystallized LTbH and LEuH with monolayered dodecyl sulfate ions vertical to the layer were synthesized by a one-step homogeneous precipitation method for the first time, and were shown to be readily delaminated in formamide. The obtained unilamellar nanosheets exhibited a decrease of the coordination number of the lanthanide ions, to probably 8-fold, when compared with the bulky precursor crystals. This change resulted in different photoluminescence emission peak shapes. Colloidal hybrids were constructed using these nanosheets as building blocks, and the emission colors of the hybrids can be facilely and precisely tuned from green to yellow, orange, and finally to red by controlling the relative contents of the two kinds of nanosheets. This method provides a novel and simple route to prepare color-tunable hybrid materials from 2-dimensional crystals. © 2013 The Royal Society of Chemistry.


Numata Y.,Japan National Institute of Materials Science | Islam A.,Japan National Institute of Materials Science | Chen H.,Shanghai University | Han L.,Japan National Institute of Materials Science | Han L.,Shanghai University
Energy and Environmental Science | Year: 2012

A new aggregation-free branch-type organic dye for dye-sensitized solar cells (DSCs) is developed by means of a twisting π-conjugation strategy. In comparison with the analogue planar dye, the twisting dye shows excellent potential as a new aggregation-free organic dye for DSCs. © 2012 The Royal Society of Chemistry.


Okada M.,Nagoya University | Sawazaki T.,Nagoya University | Watanabe K.,Japan National Institute of Materials Science | Taniguch T.,Japan National Institute of Materials Science | And 3 more authors.
ACS Nano | Year: 2014

Atomically thin transition metal dichalcogenides (TMDCs) have attracted considerable interest owing to the spin-valley coupled electronic structure and possibility in next-generation devices. Substrates are one of the most important factors to limit physical properties of atomic-layer materials, and among various substrates so far investigated, hexagonal boron nitride (hBN) is the best substrate to explore the intrinsic properties of atomic layers. Here we report direct chemical vapor deposition (CVD) growth of WS2 onto high-quality hBN using a 3-furnace CVD setup. Triangular-shaped WS2 grown on hBN have shown limited crystallographic orientation that is related to that of the underlying hBN. Photoluminescence spectra of the WS2 show an intense emission peak at 2.01 eV with a quite small fwhm of 26 meV. The sharp emission peak indicates the high quality of the present WS2 atomic layers with high crystallinity and clean interface. © 2014 American Chemical Society.


Valant M.,University of Nova Gorica | Kolodiazhnyi T.,Japan National Institute of Materials Science | Arcon I.,University of Nova Gorica | Aguesse F.,Jozef Stefan Institute | And 2 more authors.
Advanced Functional Materials | Year: 2012

An analysis of Mn substitution in SrTiO 3 is performed in order to understand the origin of reported spin coupling in lightly Mn-doped SrTiO 3. The spin glass state magnetoelectrically coupled to the dipolar glass state has previously been reported for SrTiO 3 substituted with only 2% of Mn on the B-site. An analysis of the substitution mechanism for A- and B-site doping shows a strong influence of processing conditions, such as processing temperature, oxygen partial pressure, and off-stoichiometry. The required conditions for a site-selective substitution are defined, which yield a single-phase and almost defect-free perovskite. Magnetic measurements show no magnetic anomalies resulting from spin coupling and only a simple paramagnetic behavior. Magnetic anomalies are observed only for the samples in which Mn is misplaced within the cation sublattice of the SrTiO 3 perovskite. This occurs due to improper material processing, which causes initially unpredicted changes in the valence state of the Mn and results in the formation of structural defects and irregularities associated with segregation and nucleation of the magnetic species. Previously reported spin coupling in Mn-doped SrTiO 3 is not an intrinsic phenomenon and cannot be treated as a spin glass. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Sakamoto T.,NEC Corp | Iguchi N.,NEC Corp | Aono M.,Japan National Institute of Materials Science
Applied Physics Letters | Year: 2010

The nonvolatile switch with its compact size enhances the functionality and the performance of large-scale integrated circuits. We have demonstrated a nonvolatile resistive switch with a triode of source, drain, and gate electrodes. A conduction path forms or dissolves in a solid-state ionic conductor via an electrochemical reaction, which results in turning the switch on or off. The reaction is controlled by a biasing voltage of the gate, which is separated from the conduction path by the ionic conductor. Then, the current required to turn the switch on or off is small (<2 μA). Each conductance state is nonvolatile and the ON/OFF current ratio is more than 104. We also confirm a metal precipitate between two electrodes by using element analysis. © 2010 American Institute of Physics.


Okamoto Y.,NEC Corp | Kubo Y.,Japan National Institute of Materials Science
Journal of Physical Chemistry C | Year: 2013

Ab initio molecular orbital calculations were done to examine C-O bond-breaking reactions in glyme series CH3O(CH2CH 2O)NCH3 (N = 1-4) by the attack of superoxide anion. We focused our study on N = 4 case where the reaction barrier for the bond break becomes the highest among four glymes. Intrinsic reaction coordinate calculations showed that the barrier height measured from the reaction precursor is 1.087 eV. The value is much higher than that of the analogous bond-breaking reaction in propylene carbonate. © 2013 American Chemical Society.


Yatomi M.,IHI Corporation | Tabuchi M.,Japan National Institute of Materials Science
Engineering Fracture Mechanics | Year: 2010

In this paper creep crack growth behaviour of P92 welds at 923K are presented. Creep crack growth behaviour for P92 welds are discussed with C* parameter. Creep crack growth behaviour of P92 welds has been compared with that of P91 welds with C* parameter. NSW and NSW-MOD model were compared with the experimental creep crack growth data. Plane strain NSW model significantly overestimates the crack growth rate, and plane stress NSW model underestimates it. Whilst, NSW-MOD model for plane stress and plane strain conditions gives lower and upper bound of the experimental data, respectively.FE analysis of creep crack growth has been conducted. Constrain effect for welded joints has been examined with C* line integrals of C(T) specimens. As a result, constant C* value using the material data of welded joint gives 10 times lower than that of only HAZ property. Whilst, the predicted CCG rates for welded joint are 10 times higher than those for only HAZ properties. Compared with predicted CCG rate from FE analysis and the experimental CCG rate, it can be suggested that creep crack growth tests for lower load level or for large specimen should be conducted, otherwise the experimental data should give unconservative estimation for components operated in long years. © 2010 Elsevier Ltd.


Patent
IHI Corporation and Japan National Institute of Materials Science | Date: 2016-07-27

A thermal barrier-coated Ni alloy component (10) includes: a substrate (12) made of a Ni alloy containing Al; an intermediate layer (14) formed on a surface of the substrate (12); and a thermal barrier layer (16) made of a ceramic and formed on a surface of the intermediate layer (14). The intermediate layer (14) includes a layer (18), which is formed from a -Ni_(3)Al phase on the surface on the thermal barrier layer (16) side, and contains Pt.


Patent
Japan National Institute of Materials Science, Kyowa Kogyosyo Co. and Fusokiko Co. | Date: 2010-09-10

Provided is a high-strength bolt which has a tensile strength of 1,200 MPa or more while exhibiting excellent ductility and delayed facture resistance, and further has an excellent impact toughness which had not been obtained in the conventional high-strength bolt. The high-strength bolt has a tensile strength of 1.2 GPa or more and includes a threaded portion and cylindrical neck portion. The bolt has K of 0.8 or more and satisfies Ho


Patent
IHI Corporation and Japan National Institute of Materials Science | Date: 2012-07-13

The present invention provides a high-temperature shape memory alloy, in which Hf, Zr, Ta, Nb, V, Mo, and W as a third element except Ni are added to TiPd to thereby improve high-temperature strength and exhibit large shape recovery in a high-temperature range of 200 C. to 500 C., and a method for producing the high-temperature shape memory alloy.


Patent
IHI Corporation and Japan National Institute of Materials Science | Date: 2016-02-24

A thermal barrier-coated Ni alloy component includes: a substrate made of a Ni alloy containing Al; an intermediate layer formed on a surface of the substrate; and a thermal barrier layer made of a ceramic and formed on a surface of the intermediate layer. The intermediate layer includes a layer, which is formed from a -Ni_(3)Al phase on the surface on the thermal barrier layer side, and contains Pt.


Patent
Japan National Institute of Materials Science and IHI Corporation | Date: 2014-05-21

The present invention provides a high-temperature shape memory alloy, in which Hf, Zr, Ta, Nb, V, Mo, and W as a third element except Ni are added to TiPd to thereby improve high-temperature strength and exhibit large shape recovery in a high-temperature range of 200C to 500C, and a method for producing the high-temperature shape memory alloy.


Provided is a versatile method of determining the number of layers of a two-dimensional atomic layer thin film as compared with conventional methods. An electron beam is radiated to a two-dimensional thin film atomic structure having an unknown number of layers to determine the number of layers based on an intensity of reflected electrons or secondary electrons generated thereby. In particular, this method is effective for determining the number of layers of graphene.


As the use of nanoparticles becomes more prevalent, it is clear that human exposure will inevitably increase. Considering the rapidly ageing European population and the resulting increase in the incidence of neurodegenerative diseases, there is an urgent need to address the risk presented by nanoparticles towards neurodegenerative diseases. It is believed that nanoparticles can pass through the blood-brain barrier. Once in the brain, nanoparticles have two potential major effects. They can induce oxidative activity (production of Reactive Oxygen Species), and can induce anomalous protein aggregation behaviour (fibrillation). There are multiple disease targets for the nanoparticles, including all of the known fibrillation diseases (e.g. Alzheimers and Parkinsons diseases). The factors that determine which nanoparticles enter the brain are not known. Nanoparticle size, shape, rigidity and composition are considered important, and under physiological conditions, the nature of the adsorbed biomolecule corona (proteins, lipids etc.) determines the biological responses. The NeuroNano project will investigate the detailed mechanisms of nanoparticle passage through the blood-brain barrier using primary cell co-cultures and animal studies. Using nanoparticles that are shown to reach the brain, we will determine the mechanisms of ROS production and protein fibrillation, using state-of-the-art approaches such as redox proteomics and isolation/characterisation of the critical pre-fibrillar species. Animal models for Alzheimers diseases will confirm the effects of the nanoparticles in vivo. At all stages the exact nature of the nanoparticle biomolecule corona will be determined. The result will be a risk-assessment framework for assessing the safety of nanoparticles towards neurodegenerative diseases, based on the connection of their biological effects to their biomolecule corona, which determines the biological response in vivo and reports on the nanoparticles history.


Yang X.,Japan National Institute of Materials Science | Yanagida M.,Japan National Institute of Materials Science | Han L.,Japan National Institute of Materials Science | Han L.,Shanghai JiaoTong University
Energy and Environmental Science | Year: 2013

Dye-sensitized solar cells (DSCs) have attracted great interest as potential candidates of "low cost solar cells" in the solution of global energy demand. To accelerate the progress of DSCs, it is important to evaluate device performance with reliable measurements that will enable more effective comparison and application of new findings in materials and technologies by different research groups. In this perspective, we review existing measurement methods and summarize the appropriate techniques for the evaluation of DSCs based mainly on our experience, which helped us to obtain reliable results close to those certified by public test centres. The key factors in the measurements that correlate to device performance are discussed, including the calibration of the solar simulator using reference cells, the measurement time of the current-voltage characteristics and the incident photon-to-current conversion efficiency, and the area for determination with a proper shading mask. We demonstrate the causes and solutions of measurement errors in the results of device performance, such as short circuit photocurrent density, open circuit voltage, fill factor, and energy conversion efficiency. Finally, a list of appropriate measurements for a more reliable evaluation of DSCs is proposed. © The Royal Society of Chemistry 2013.


Sakurai H.,Japan National Institute of Materials Science | Kolodiazhnyi T.,Japan National Institute of Materials Science | Michiue Y.,Japan National Institute of Materials Science | Takayama-Muromachi E.,Japan National Institute of Materials Science | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2012

Spin frustration and the unusual electronic state of Cr 4+ ions are the origins of unconventional colossal magnetoresistance (CMR) in NaCr 2O 4, a new member of the rare mixed-valence chromium oxides. CMR materials have previously been limited to almost only manganese oxides; the discovery of the CMR in a non-manganese-based material opens a new dimension in the quest for novel CMR materials. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Panaccione G.,CNR Institute of Materials | Kobayashi K.,Hiroshima University | Kobayashi K.,Japan National Institute of Materials Science
Surface Science | Year: 2012

The electronic properties of surfaces and buried interfaces can vary considerably in comparison to the bulk. In turn, analyzing bulk properties, without including those of the surface, is understandably challenging. Hard X-ray photoelectron spectroscopy (HAXPES) allows the well known ability of photoemission to interrogate the electronic structure of material systems with bulk volume sensitivity. This is achieved by tuning the kinetic energy range of the analyzed photoelectrons in the multi-keV regime. This unique ability to probe truly bulk properties strongly compliments normal photoemission, which generally probes surface electronic structure that is different than the bulk selected examples of HAXPES and possible implications towards the study of complex oxide-based interfaces and highly correlated systems are discussed. © 2011 Elsevier B.V. All rights reserved.


Shrestha L.K.,Japan National Institute of Materials Science | Yamamoto M.,Yokohama National University | Arima S.,Mitsubishi Group | Aramaki K.,Yokohama National University
Langmuir | Year: 2011

We report a facile method for the formation of charge-free reverse wormlike micelles in a nonionic surfactant/oil system without addition of water under ambient conditions. This route involves the addition of sucrose dioleate (SDO) to semidilute solutions of sucrose trioleate (STO) in hexadecane. A reverse wormlike micelle was possible to achieve only with ionic surfactants in which water and/or salts are fundamentally required to induce micellar growth so far. In this contribution, we have shown that less lipophilic nonionic surfactant SDO promotes one-dimensional growth to STO reverse micelles and leads to the formation of transient networks of viscoelastic reverse wormlike micelles. The zero-shear viscosity increases by ∼4 orders of magnitude, and it is the mixing fraction of SDO to STO that determines the viscosity growth. The structure and dynamics of the reverse micelles are confirmed by small-angle X-ray scattering (SAXS) and rheometry measurements. © 2011 American Chemical Society.


Numata Y.,Japan National Institute of Materials Science | Singh S.P.,Indian Institute of Chemical Technology | Islam A.,Japan National Institute of Materials Science | Iwamura M.,University of Toyama | And 4 more authors.
Advanced Functional Materials | Year: 2013

A novel Ru π-expanded terpyridyl sensitizer, referred to as HIS-2, is prepared based on the molecular design strategy of substitution with a moderately electron-donating 4-methylstyryl group onto the terpyridyl ligand. The HIS-2 dye exhibits a slightly increased metal-to-ligand charge transfer (MLCT) absorption at around 600 nm and an intense π-π* absorption in the UV region compared with a black dye. Density functional theory calculations reveal that the lowest unoccupied molecular orbital (LUMO) is distributed over the terpyridine and 4-methylstyryl moieties, which enhances the light-harvesting capability and is appropriate for smooth electron injection from the dye to the TiO2 conduction band. The incident photon-to-electricity conversion efficiency spectrum of HIS-2 exhibits better photoresponse compared with black dye over the whole spectral region as a result of the extended π-conjugation. A DSC device based on black dye gives a short-circuit current (JSC) of 21.28 mA cm-2, open-circuit voltage (VOC) of 0.69 V, and fill factor (FF) of 0.72, in an overall conversion efficiency (η) of 10.5%. In contrast, an HIS-2 based cell gives a higher JSC value of 23.07 mA cm-2 with VOC of 0.68 V, and FF of 0.71, and owing to the higher JSC value of HIS-2, an improved η value of 11.1% is achieved. Moderate electron-donating substituents are important for enhancement of the light harvesting capability of Ru(II) sensitizers. Substitution of a terpyridyl ligand with a 4-methylstyryl group increases the molecular absorption coefficient from the UV to the NIR region compared with black dye owing to the wider lowest unoccupied molecular orbital (LUMO) distributed over the terpyridyl and extended π-conjugation. The intense absorption gives a high JSC of 23.07 mA cm-2, and a resulting overall conversion efficiency of 11.1%. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Bunz J.,University of Munster | Brink T.,TU Darmstadt | Tsuchiya K.,Japan National Institute of Materials Science | Meng F.,Japan National Institute of Materials Science | And 2 more authors.
Physical Review Letters | Year: 2014

The low temperature heat capacity of amorphous materials reveals a low-frequency enhancement (boson peak) of the vibrational density of states, as compared with the Debye law. By measuring the low-temperature heat capacity of a Zr-based bulk metallic glass relative to a crystalline reference state, we show that the heat capacity of the glass is strongly enhanced after severe plastic deformation by high-pressure torsion, while subsequent thermal annealing at elevated temperatures leads to a significant reduction. The detailed analysis of corresponding molecular dynamics simulations of an amorphous Zr-Cu glass shows that the change in heat capacity is primarily due to enhanced low-frequency modes within the shear band region. © 2014 American Physical Society.


Bi E.,Shanghai JiaoTong University | Chen H.,Shanghai JiaoTong University | Yang X.,Japan National Institute of Materials Science | Peng W.,Japan National Institute of Materials Science | And 3 more authors.
Energy and Environmental Science | Year: 2014

A novel conductive catalyst was designed based on a quasi core-shell structure of N-doped graphene/cobalt sulfide. This platinum-free catalyst shows high catalytic activity and conductivity owing to close interactions between the core (cobalt sulphide) and the shell (N-doped graphene). It enables dye-sensitized solar cells (DSSCs) to obtain high energy conversion efficiency up to 10.71%, which is as far as we know the highest efficiency for DSSCs based on a platinum-free counter electrode. This journal is © the Partner Organisations 2014.


Wu Y.,Japan National Institute of Materials Science | Islam A.,Japan National Institute of Materials Science | Yang X.,Japan National Institute of Materials Science | Qin C.,Japan National Institute of Materials Science | And 5 more authors.
Energy and Environmental Science | Year: 2014

On a planar substrate the sequential deposition of CH3NH 3PbI3 perovskite is optimized by retarding the crystallization of PbI2. This strategy overcomes the problem of incomplete conversion and uncontrolled particle sizes of perovskite in the absence of mesoporous scaffolds, greatly increasing the film reproducibility. Highly efficient and reproducible planar-structured perovskite solar cells were obtained with the best efficiency of 13.5%, average efficiency of 12.5% and a small standard deviation of 0.57 from a total of 120 cells. This journal is © the Partner Organisations 2014.


Ohtake A.,Japan National Institute of Materials Science | Hagiwara A.,University of Electro - Communications | Nakamura J.,University of Electro - Communications
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

A combined experimental and theoretical study on the incorporation of Mn in GaAs has been presented. We have successfully controlled the location of Mn atoms at GaAs(001) surfaces by changing the surface atomic geometry. While Mn atoms prefer to substitute Ga sites at a subsurface layer under the As-rich conditions, the incorporation into interstitial sites becomes more favorable as the surface As coverage is decreased. The present results provide a mechanism for the enhanced incorporation of substitutional Mn atoms in GaMnAs under low-temperature (i.e., As-rich) growth conditions. © 2013 American Physical Society.


Shi Y.,Fudan University | Shi Y.,University of Wollongong | Wang J.-Z.,University of Wollongong | Chou S.-L.,University of Wollongong | And 5 more authors.
Nano Letters | Year: 2013

To explore good anode materials of high safety, high reversible capacity, good cycling, and excellent rate capability, a Li3VO4 microbox with wall thickness of 40 nm was prepared by a one-pot and template-free in situ hydrothermal method. In addition, its composite with graphene nanosheets of about six layers of graphene was achieved. Both of them, especially the Li3VO4/graphene nanosheets composite, show superior electrochemical performance to the formerly reported vanadium-based anode materials. The composite shows a reversible capacity of 223 mAh g -1 even at 20C (1C = 400 mAh g-1). After 500 cycles at 10C there is no evident capacity fading. © 2013 American Chemical Society.


Sampath S.,State University of New York at Stony Brook | Schulz U.,German Aerospace Center | Jarligo M.O.,Jülich Research Center | Kuroda S.,Japan National Institute of Materials Science
MRS Bulletin | Year: 2012

Thermal-barrier coatings (TBCs) are complex, defected, thick films made of zirconia-based refractory ceramic oxides. Their widespread applicability has necessitated development of high throughput, low cost materials manufacturing technologies. Thermal plasmas and electron beams have been the primary energy sources for processing of such systems. Electron-beam physical vapor deposition (EBPVD) is a sophisticated TBC fabrication technology for rotating parts of aero engine components, while atmospheric plasma sprays (APS) span the range from rotating blades of large power generation turbines to afterburners in supersonic propulsion engines. This article presents a scientific description of both contemporary manufacturing processes (EBPVD, APS) and emerging TBC deposition technologies based on novel extensions to plasma technology (suspension spray, plasma spray-PVD) to facilitate novel compliant and low thermal conductivity coating architectures. TBCs are of vital importance to both performance and energy efficiency of modern turbines with concomitant needs in process control for both advanced design and reliable manufacturing. © 2012 Materials Research Society.


Peng W.,Japan National Institute of Materials Science | Han L.,Japan National Institute of Materials Science | Han L.,Shanghai JiaoTong University
Journal of Materials Chemistry | Year: 2012

Anatase TiO2 microplates with hexagonal shape were synthesized by a hydrothermal method in water-ethanol solvent. The single-crystalline TiO2 microplate film exhibited high reflectance in the visible region due to the unique planar morphology. When used as the scattering overlayer in dye-sensitized solar cells (DSCs), such microplates effectively enhanced light harvesting and led to the increase of the photocurrent of the DSCs. As a result, a 16.3% improvement in conversion efficiency was achieved after introducing the TiO2 microplate scattering layer (7.91%), which also surpassed the commercial scattering overlayer. The comparative experiments between the microplates and TiO2 microrods further confirmed that such a planar morphology is more beneficial to light scattering and photovoltaic performance. The excellent light-scattering properties of plate-like TiO2 make it a promising candidate as a scattering material for DSCs. © 2012 The Royal Society of Chemistry.


Pratt A.,University of York | Pratt A.,Japan National Institute of Materials Science | Lari L.,University of York | Hovorka O.,University of York | And 6 more authors.
Nature Materials | Year: 2014

Geometry and confinement effects at the nanoscale can result in substantial modifications to a material's properties with significant consequences in terms of chemical reactivity, biocompatibility and toxicity. Although benefiting applications across a diverse array of environmental and technological settings, the long-term effects of these changes, for example in the reaction of metallic nanoparticles under atmospheric conditions, are not well understood. Here, we use the unprecedented resolution attainable with aberration-corrected scanning transmission electron microscopy to study the oxidation of cuboid Fe nanoparticles. Performing strain analysis at the atomic level, we reveal that strain gradients induced in the confined oxide shell by the nanoparticle geometry enhance the transport of diffusing species, ultimately driving oxide domain formation and the shape evolution of the particle. We conjecture that such a strain-gradient-enhanced mass transport mechanism may prove essential for understanding the reaction of nanoparticles with gases in general, and for providing deeper insight into ionic conductivity in strained nanostructures. © 2014 Macmillan Publishers Limited.


Sato K.,Osaka University | Bergqvist L.,Uppsala University | Kudrnovsky J.,ASCR Institute of Physics Prague | Dederichs P.H.,Jülich Research Center | And 9 more authors.
Reviews of Modern Physics | Year: 2010

This review summarizes recent first-principles investigations of the electronic structure and magnetism of dilute magnetic semiconductors (DMSs), which are interesting for applications in spintronics. Details of the electronic structure of transition-metal-doped III-V and II-VI semiconductors are described, especially how the electronic structure couples to the magnetic properties of an impurity. In addition, the underlying mechanism of the ferromagnetism in DMSs is investigated from the electronic structure point of view in order to establish a unified picture that explains the chemical trend of the magnetism in DMSs. Recent efforts to fabricate high- TC DMSs require accurate materials design and reliable TC predictions for the DMSs. In this connection, a hybrid method (ab initio calculations of effective exchange interactions coupled to Monte Carlo simulations for the thermal properties) is discussed as a practical method for calculating the Curie temperature of DMSs. The calculated ordering temperatures for various DMS systems are discussed, and the usefulness of the method is demonstrated. Moreover, in order to include all the complexity in the fabrication process of DMSs into advanced materials design, spinodal decomposition in DMSs is simulated and we try to assess the effect of inhomogeneity in them. Finally, recent works on first-principles theory of transport properties of DMSs are reviewed. The discussion is mainly based on electronic structure theory within the local-density approximation to density-functional theory. © 2010 The American Physical Society.


Grant
Agency: European Commission | Branch: FP7 | Program: CP-IP | Phase: NMP-2010-1.3-1 | Award Amount: 12.48M | Year: 2011

While there are standard procedures for product life cycle analysis, exposure, hazard, and risk assessment for traditional chemicals, is not yet clear how these procedures need to be modified to address all the novel properties of nanomaterials. There is a need to develop specific reference methods for all the main steps in managing the potential risk of ENM. The aim of MARINA is to develop such methods. MARINA will address the four central themes in the risk management paradigm for ENM: Materials, Exposure, Hazard and Risk. The methods developed by MARINA will be (i) based on beyond-state-of-the-art understanding of the properties, interaction and fate of ENM in relation to human health and the quality of the environment and will either (ii) be newly developed or adapted from existing ones but ultimately, they will be compared/validated and harmonised/standardised as reference methods for managing the risk of ENM. MARINA will develop a strategy for Risk Management including monitoring systems and measures for minimising massive exposure via explosion or environmental spillage.


Patent
Mitsubishi Group and Japan National Institute of Materials Science | Date: 2015-06-11

Phosphors include a CaAlSiN_(3 )family crystal phase, wherein the CaAlSiN_(3 )family crystal phase comprises at least one element selected from the group consisting of Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb.


Patent
Mitsubishi Group and Japan National Institute of Materials Science | Date: 2013-04-03

An object of the present invention is to provide an inorganic phosphor having fluorescence properties emitting an orange or red light which has a longer wavelength as compared with the cases of conventional sialon phosphors activated with a rare earth. The invention relates to a design of white light-emitting diode rich in a red component and having good color-rendering properties by employing a solid solution crystal phase phosphor which uses as a host crystal an inorganic compound having the same crystal structure as that of a CaSiAlN_(3) crystal phase and to which M Element (wherein M Element is one or two or more elements selected from the group consisting of Mn, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) is added as an emission center.


Grant
Agency: GTR | Branch: EPSRC | Program: | Phase: Research Grant | Award Amount: 438.49K | Year: 2015

The isolation of single-atomic layer graphene has led to a surge of interest in other layered crystals with strong in-plane bonds and weak, van der Waals-like, interlayer coupling. A variety of two-dimensional (2D) crystals have been investigated, including large band gap insulators and semiconductors with smaller band gaps such as transition metal dichalcogenides. Interest in these systems is motivated partly by the need to combine them with graphene to create field effect transistors with high on-off switching ratios. More importantly, heterostructures made by stacking different 2D crystals on top of each other provide a platform for creating new artificial crystals with potential for discoveries and applications. The possibility of making van der Waals heterostructures has been demonstrated experimentally only for a few 2D crystals. However, some of the currently available 2D layers are unstable under ambient conditions, and those that are stable offer only limited functionalities, i.e. low carrier mobility, weak optical emission/absorption, band gaps that cannot be tuned, etc. In a recent series of pilot experiments, we have demonstrated that nanoflakes of the III-VI layer compound, InSe, with thickness between 5 and 20 nanometers, have a thickness-tuneable direct energy gap and a sufficiently high chemical stability to allow us to combine them with graphene and related layer compounds to make heterostructures with novel electrical and optical properties. The main goal of this project is to develop graphene-hybrid heterostructures based on this novel class of two-dimensional (2D) III-VI van der Waals crystals. This group of semiconductors will enrich the current library of 2D crystals by overcoming limitations of currently available 2D layers and by offering a versatile range of electronic and optical properties. From the growth and fabrication of new systems to the demonstration of prototype devices, including vertical tunnel transistors and optical-enhanced-microcavity LEDs, our project will provide a platform for scientific investigations and will contribute to the technology push required to create new routes to device miniaturization, fast-electronics, sensing and photonics. There is great potential for further growth of all these sectors as the fabrication of 2D systems improves and as new properties are discovered and implemented in functional devices.


Wang W.,Japan National Institute of Materials Science | Wang W.,CAS Institute of Physics | Sukegawa H.,Japan National Institute of Materials Science | Inomata K.,Japan National Institute of Materials Science
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

Spin-valve-type epitaxial magnetic tunnel junctions (MTJs) consisting of a full-Heusler alloy Co2FeAl (CFA) and a MgO tunnel barrier were fabricated on a single-crystal MgO(001) substrate using sputtering method for all the layers. Experimental temperature-dependent tunnel magnetoresistance in the MTJs was revealed to be fitted well using spin wave excitation model for tunneling spin polarization, P (T) = P0 (1-α T3/2) up to room temperature, where P0 is the spin polarization at 0 K and α is a fitting parameter. The determined P and α are shown to be significantly different between bottom and top CFA electrodes facing a MgO barrier. It is demonstrated that the bottom CFA deposited on a Cr buffer has a low α and behaves as a half-metal with P∼1 in terms of the Δ1 symmetry due to the coherent tunneling through a MgO barrier. © 2010 The American Physical Society.


Salunkhe R.R.,Japan National Institute of Materials Science | Lin J.,University of Wollongong | Malgras V.,University of Wollongong | Dou S.X.,University of Wollongong | And 2 more authors.
Nano Energy | Year: 2015

Coaxial carbon nanotube-nickel hydroxide (CNT/Ni(OH)2) composites are prepared by a simple, one step and inexpensive chemical coprecipitation method. The coaxial coating of nickel hydroxide provides a three dimensional (3D) structure for easy access of electrolyte. Asymmetric supercapacitors (ASCs) are fabricated using coaxial CNT/Ni(OH)2 composites as positive electrode and reduced graphene oxide (rGO) as negative electrode. The operation voltage is expanded to 1.8V in spite of the use of aqueous electrolyte, revealing a high energy density of 35W·h·kg-1 at a power density of 1.8kW·kg-1. This strategy for choice of coaxial metal hydroxide CNT composites provides a promising route for next generation supercapacitors with high energy as well as power densities. © 2014 Elsevier Ltd.


Patent
Japan National Institute of Materials Science and Oshigane Inc | Date: 2012-05-02

[Problem to be Solved] The present invention relates to rationalization of a disassembling operation of electronic devices before crushing the devices in order to achieve urban mines, and has an object to achieve mechanical disassembling without significantly destroying components containing many rare elements to be recovered. [Solution] In order to achieve the object, the invention 1 provides a casing disassembling apparatus including: a first rotor and a second rotor journaled on a rotating shaft, and having end surfaces perpendicular to the rotating shaft, wherein the end surfaces face each other, the rotors are placed so that the end surfaces are inclined to each other, a portion at which a space between the end surfaces is larger than at the other portion is an input port of an object to be disassembled, and the other portion is a portion at which a pressurizing force is applied to the input object to be disassembled, and from which a disassembled piece is ejected. The invention 2 provides the casing disassembling apparatus, wherein a plurality of protrusions are mounted to at least one of the end surfaces in the invention 1. The invention 3 provides the casing disassembling apparatus, wherein protrusions are provided on a periphery of one of the end surfaces at predetermined intervals corresponding to a size of the ejected disassembled piece in the invention 2. The invention 4 provides a disassembling method using a casing disassembling apparatus according to any one of the inventions 1 to 3, wherein a relative inclination angle and an inclination angle to the vertical of end surfaces are adjusted to set a space of an input port and a pressurizing force correspondingly to an object to be disassembled such as an electronic device. According to the present invention, a casing can be crushed without components containing rare metal being crushed to a level that the components cannot be recovered. Also, an electronic device can be mechanically disassembled so that the casing and the components can be disconnected from each other and can be separately recovered.


Patent
Japan National Institute of Materials Science and Mitsubishi Group | Date: 2013-07-30

Provided is a Ni-based single crystal superalloy containing


Patent
Japan National Institute of Materials Science and Mitsubishi Group | Date: 2011-10-26

The Ni-based single crystal alloy disclosed here is a single crystal and has a chemical composition containing, as % by mass,Co: 8 to 12%, Cr: 5 to 7.5%, Mo: 0.2 to 1.2%,W: 5 to 7%, AI: 5 to 6.5%, Ta: 8 to 12%.Hf: 0.01 to 0.2%, Re: 2 to 4%, Si: 0.005 to 0.1%,with the balance of Ni and inevitable impurities.


Sha J.B.,Beihang University | Sha J.B.,Japan National Institute of Materials Science | Yamabe-Mitarai Y.,Japan National Institute of Materials Science
Intermetallics | Year: 2013

This paper investigates the strength response of Ir-xHf-yNb alloys (x = 3, 4, 5, 8, 9, 10 at.%, and y = 5, 6, 7, 11, 13, 15 at.%) with a dual-phase fcc/L1 2 microstructure at room and high temperatures. The experimental strength at 1950 °C was compared with that obtained by the rule of mixture. The results showed that in the fcc/L1 2 structure the fcc phase always shows higher strength than the L1 2 phase, at both room and high temperatures. A dual-phase fcc/L1 2 microstructure with different fcc to L1 2 fraction ratio formed when Hf and Nb contents in the Ir-xHf-yNb ternary alloys were larger than 3 at.% and 5 at.%, respectively, and the pure L1 2 microstructure was obtained at 10 at.% Hf and 15 at.% Nb. The Ir-5Hf-7Nb alloy, possessing an fcc-dominant microstructure in which the optimization fcc fraction is about 78%, has an outstanding 0.2% yield compressive strength of 270 MPa even at 1950 °C. This ultra-high strength is attributed to strong interface hardening by the large lattice misfit between the fcc and L1 2 phases. The failure mode of the Ir-Hf-Nb ternary alloys is by debonding of the grain boundary. © 2012 Elsevier Ltd. All rights reserved.


Ishikawa R.,Oak Ridge National Laboratory | Lupini A.R.,Oak Ridge National Laboratory | Findlay S.D.,Monash University | Taniguchi T.,Japan National Institute of Materials Science | Pennycook S.J.,University of Tennessee at Knoxville
Nano Letters | Year: 2014

Materials properties, such as optical and electronic response, can be greatly enhanced by isolated single dopants. Determining the full three-dimensional single-dopant defect structure and spatial distribution is therefore critical to understanding and adequately tuning functional properties. Combining quantitative Z-contrast scanning transmission electron microscopy images with image simulations, we show the direct determination of the atomic-scale depth location of an optically active, single atom Ce dopant embedded within wurtzite-type AlN. The method represents a powerful new tool for reconstructing three-dimensional information from a single, two-dimensional image. © 2014 American Chemical Society.


Shen Y.,Nanjing Southeast University | Nakanishi T.,Japan National Institute of Materials Science
Physical Chemistry Chemical Physics | Year: 2014

Manipulating molecular interaction and assembly for developing various functional nanostructures with controlled dimensionality, morphology and tailored properties is currently a research focus in molecular science and materials chemistry. Particularly, the self-organization of fullerenes (i.e. C60) to form various functional assemblies has received intense interest since it can provide excellent optoelectronic properties for photo-energy conversion-induced applications such as solar cells and field effect transistors (FET). In this perspective, we describe our recent efforts toward the development in the area of fullerene molecular design and assemblies aimed at improving the photoconductivity and photo-energy (electric and thermal) conversion systems. This journal is © the Partner Organisations 2014.


Ohtsu H.,Pohang University of Science and Technology | Choi W.,Pohang University of Science and Technology | Islam N.,Pohang University of Science and Technology | Matsushita Y.,Japan National Institute of Materials Science | Kawano M.,Pohang University of Science and Technology
Journal of the American Chemical Society | Year: 2013

S3 is one of the basic allotropes of sulfur but is still a mysterious labile species. We selectively trapped S3 in a pore of a thermally stable coordination network and determined S3 structure by ab initio X-ray powder diffraction analysis. S3 in a pore has a C2v bent structure. The network containing trapped S3 is remarkably stable under ambient conditions and is inert to photoirradiation. S3 in the network could be transformed to S6 by mechanical grinding or heating in the presence of NH4X (X = Cl or Br). S 6 could be reverse-transformed to S3 by photoirradiation. We also determined the structure of the network containing S6 by ab initio X-ray powder diffraction analysis. © 2013 American Chemical Society.


Oh-Ishi K.,Japan National Institute of Materials Science | Edalati K.,Kyushu University | Kim H.S.,Pohang University of Science and Technology | Hono K.,Japan National Institute of Materials Science | Horita Z.,Kyushu University
Acta Materialia | Year: 2013

This study reports that solid-state reactions occur by the application of high-pressure torsion (HPT) to the Al-Cu system even at low homologous temperature. A bulk form of disc consisting of two separate half-discs of pure Al and pure Cu are processed by HPT at ambient temperature under a pressure of 6 GPa. X-ray diffraction analysis and high-resolution transmission electron microscopy confirm the formation of different intermetallic phases such as Al2Cu, AlCu and Al4Cu9, as well as the dissolution and supersaturation of Al and Cu in each matrix. It is shown that the diffusion coefficient is enhanced by 1012-1022 times during the HPT processing in comparison with the lattice diffusion and becomes comparable to the surface diffusion. The enhanced diffusion is attributed to the presence of a high density of lattice defects such as vacancies, dislocations and grain boundaries produced by HPT processing. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Ozaki T.,Japan Advanced Institute of Science and Technology | Nishio K.,Japan National Institute of Advanced Industrial Science and Technology | Weng H.,Japan Advanced Institute of Science and Technology | Kino H.,Japan National Institute of Materials Science
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

By first principle calculations, a dual spin filter effect under finite bias voltages is demonstrated in an antiferromagnetic junction of symmetric zigzag graphene nanoribbon (ZGNR). Unlike conventional spin filter devices using half metallic materials, the up and down-spin electrons are unidirectionally filtered in the counter direction of the bias voltage, making the junction a dual spin filter. On the contrary, asymmetric ZGNRs do not exhibit such a spin filter effect. By analyzing Wannier functions and a tight-binding model, we clarify that an interplay between the spin polarized band structure of π and π- states near the Fermi level and decoupling of the interband hopping of the two states, arising from the symmetry of the wave functions, plays a crucial role in the effect. © 2010 The American Physical Society.


Ozaki T.,Japan Advanced Institute of Science and Technology | Nishio K.,Japan National Institute of Advanced Industrial Science and Technology | Kino H.,Japan National Institute of Materials Science
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

An efficient implementation of the nonequilibrium Green function method combined with the density-functional theory, using localized pseudoatomic orbitals, is presented for electronic transport calculations of a system connected with two leads under a finite bias voltage. In the implementation, accurate and efficient methods are developed especially for the evaluation of the density matrix and treatment of boundaries between the scattering region and the leads. Equilibrium and nonequilibrium contributions in the density matrix are evaluated with very high precision by a contour integration with a continued fraction representation of the Fermi-Dirac function and by a simple quadrature on the real axis with a small imaginary part, respectively. The Hartree potential is computed efficiently by a combination of the two-dimensional fast Fourier transform and a finite difference method, and the charge density near the boundaries is constructed with a careful treatment to avoid the spurious scattering at the boundaries. The efficiency of the implementation is demonstrated by rapid convergence properties of the density matrix. In addition, as an illustration, our method is applied for zigzag graphene nanoribbons, a Fe/MgO/Fe tunneling junction, and a LaMnO3 / SrMnO3 superlattice, demonstrating its applicability to a wide variety of systems. © 2010 The American Physical Society.


A ZnO single crystal can be grown on a seed crystal substrate using a liquid phase epitaxial growth method by mixing and melting ZnO as a solute and a solvent, bringing the crystal substrate into direct contact with the resultant melt, and pulling up the seed crystal substrate continuously or intermittently. A self-supporting Mg-containing ZnO mixed single crystal wafer can be obtained as follows. A Mg-containing ZnO mixed single crystal is grown using a liquid phase epitaxial growth method by mixing and melting ZnO and MgO forming a solute and a solvent, then bringing a seed crystal substrate into direct contact with the resultant melt, and pulling up the seed crystal substrate continuously or intermittently. Then, the self-supporting Mg-containing ZnO mixed single crystal wafer is obtained by removing the substrate by polishing or etching, and polishing or etching a surface, on the side of -c plane, of the single crystal grown by the liquid phase epitaxial growth method.


Patent
Japan National Institute of Materials Science and ROHM Semiconductor | Date: 2010-02-17

A measuring chip is configured for separating and measuring a target component in a sample by rotation around first and second axes of rotation. The measuring chip includes a centrifugal separation tube that centrifugally separates the target component from the sample by rotating the measuring chip around the first axis of rotation; a first holding section installed in the bottom of the centrifugal separation tube, wherein non-target components other than the target component in the sample are introduced therein by rotation around the first axis of rotation, and the first holding section holds the non-target components during rotation around the second axis of rotation; and a measuring section connected to one end of the centrifugal separation tube that measures the non-target components introduced from the centrifugal separation tube by rotation around the second axis of rotation.


Naganuma T.,Japan National Institute of Materials Science | Naito K.,Japan National Institute of Materials Science | Yang J.-M.,University of California at Los Angeles
Carbon | Year: 2011

The effect of polyimide coatings on the filament tensile strength of high-strength polyacrylonitrile-based carbon fiber was studied by using dip and high-temperature vapor deposition polymerization (VDP) coating processes. Unlike a VDP on a cold substrate, high-temperature VDP has the potential to directly synthesize and isotropically deposit a polyimide, from diamine and dihydride monomers without any by-products, on a substrate heated up to 200 °C. The average filament tensile strength of the flaw-sensitive carbon fiber improved with all the polyimide coatings used. Nevertheless, for the same monomers, the high-temperature VDP coating process was advantageous for high-efficiency surface flaw healing compared to the dip-coating process, resulting in a 25% increase in the average tensile strength of the carbon fiber. These results were evident not only for the carbon fibers without artificial nano-notches but also for those with artificial notches less than 30 nm in depth. Thus, we clearly showed the potential for the VDP polyimide coating to heal surface nano-flaws of the carbon fiber. The different infiltrations of the coating into nano-notches and its effect on the filament tensile properties were characterized, as well as discussing the impact of the VDP coating with an interlayer between the coating and the fiber. © 2011 Elsevier Ltd. All rights reserved.


Kameoka S.,Tohoku University | Tsai A.-P.,Tohoku University | Tsai A.-P.,Japan National Institute of Materials Science
Journal of Materials Chemistry | Year: 2010

Nanoporous gold fabricated by the dealloying of binary Au alloys has a three-dimensional network of fine ligaments on the nano-scale, which is a novel unsupported gold catalyst with exceptional catalytic activity for CO oxidation. Here we report a new nanoporous structure - a composite formed by alternately layered Au/Fe3O4/Au with layer spacing ∼200 nm and with porous structure (the pore size is below 20 nm). The Au/Fe 3O4/Au revealed much higher catalytic performance for CO oxidation than the previously reported conventional Au/Fe2O 3 catalyst, where the porous Au and porous Fe3O 4 were responsible for the high activity and high thermal stability, respectively. The porous structure is formed via a self-assembly process by the dealloying of Al in a NaOH aqueous solution for a conventionally melting Al-Au-Fe alloy precursor with an alternately layered Al2Au/Al 2Fe/Al2Au structure. We show here, that a fine composite nanoporous structure could be intentionally designed on the basis of the metallurgically tailored microstructure of the precursor alloy. © 2010 The Royal Society of Chemistry.


Sakuma H.,Japan National Institute of Materials Science | Ichiki M.,Tohoku University
Geofluids | Year: 2016

We report on molecular dynamics (MD) simulations for predicting the density and isothermal compressibility of an H2O-NaCl fluid as a function of temperature (673-2000 K), pressure (0.2-2.0 GPa), and salt concentration (0.0-21.9 wt%). The atomistic behavior was analyzed via the hydration number of ions and number of ion pairs. Hydration numbers of Na+ and Cl- increased with increasing pressure and decreasing temperature. Conversely, the fraction of Na-Cl ion pairs increased with decreasing pressure and increasing temperature. This hydration and association behavior is consistent with the low dielectric constant of H2O under these conditions. The presence of polynuclear clusters of Na-Cl was confirmed at high temperatures, low pressures, and high salt concentrations. We propose a purely empirical equation of state (EoS) for H2O-NaCl fluids under high temperatures and pressures that should be useful for estimating the fluid distribution in Earth's crust and upper mantle in relation to effects on earthquakes and volcanic eruptions. © 2016 John Wiley & Sons Ltd.


Tsai A.-P.,Tohoku University | Tsai A.-P.,Japan National Institute of Materials Science
Chemical Society Reviews | Year: 2013

The geometrical concept and structural framework of quasicrystals (QCs) were established shortly after the discovery of QCs. Specifically, the static and dynamic properties of the atoms and the electronic structures of quasiperiodic lattices were theoretically developed. Experimental studies lagged behind theoretical progress due to the lack of suitable samples. This situation changed with the discovery of several highly ordered stable QCs. Studies of these new QCs have provided new insights into the structure and properties of QCs. This article chronologically reviews the discoveries of various stable icosahedral QCs and subsequent studies that determined their structures, properties, and stabilization mechanisms. © 2013 The Royal Society of Chemistry.


Estili M.,Japan National Institute of Materials Science | Kawasaki A.,Tohoku University | Sakka Y.,Japan National Institute of Materials Science
Advanced Materials | Year: 2012

A highly concentrated 3D macrostructure of individual multiwalled carbon nanotubes (MWCNTs) is practically realized in a ceramic environment with poreless/intimate interfaces by a scalable aqueous colloidal approach. This concept dramatically improves not only the transport property and network connectivity of the MWCNT 3D macrostructures (a DC-conductivity of nearly 5000 S m-1) but also the strain tolerance of the ceramic environment. Such low-cost and novel MWCNT/ceramic hybrids have many potential functional and structural applications. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Stieg A.Z.,University of California at Los Angeles | Stieg A.Z.,Japan National Institute of Materials Science | Avizienis A.V.,University of California at Los Angeles | Sillin H.O.,University of California at Los Angeles | And 4 more authors.
Advanced Materials | Year: 2012

Recent advances in the neuromorphic operation of atomic switches as individual synapse-like devices demonstrate the ability to process information with both short-term and long-term memorization in a single two terminal junction. Here it is shown that atomic switches can be self-assembled within a highly interconnected network of silver nanowires similar in structure to Turing's "B-Type unorganized machine", originally proposed as a randomly connected network of NAND logic gates. In these experimental embodiments, complex networks of coupled atomic switches exhibit emergent criticality similar in nature to previously reported electrical activity of biological brains and neuron assemblies. Rapid fluctuations in electrical conductance display metastability and power law scaling of temporal correlation lengths that are attributed to dynamic reorganization of the interconnected electro-ionic network resulting from induced non-equilibrium thermodynamic instabilities. These collective properties indicate a potential utility for real-time, multi-input processing of distributed sensory data through reservoir computation. We propose these highly coupled, nonlinear electronic networks as an implementable hardware-based platform toward the creation of physically intelligent machines. A complex, self-assembled network of highly interconnected atomic switches similar in structure to Turing's "B-Type unorganized machine" exhibits emergent criticality similar in nature to the electrical activity of biological brains and neuron assemblies. Power law scaling of rapid fluctuations in electrical conductance indicates a potential utility in hardware-based implementations of real-time, multi-input processing through reservoir computation. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Suehiro T.,Tohoku University | Hirosaki N.,Japan National Institute of Materials Science | Xie R.-J.,Japan National Institute of Materials Science
ACS Applied Materials and Interfaces | Year: 2011

We have developed a new Ce 3+-activated nitride phosphor, (La,Ca) 3Si 6N 11:Ce 3+, using the gas-reduction-nitridation method. The synthesized (La,Ca) 3Si 6N 11:Ce 3+ possesses tunable yellow broadband emission with the dominant wavelength of 577-581 nm and the external quantum efficiency up to ∼42%, under an excitation of 450 nm. Precise steady-state and time-resolved photoluminescence analyses revealed that the only one type of Ce 3+ center is active under the blue-light excitation. By combining the synthesized (La,Ca) 3Si 6N 11:Ce 3+ phosphors with the 450-nm InGaN chip, a broad range of white light with the correlated color temperatures of ∼2600-3800 K can be created, demonstrating their promising applicability to the warm-white light-emitting diodes. © 2011 American Chemical Society.


Kim J.,Japan National Institute of Materials Science | Sinha J.,Japan National Institute of Materials Science | Hayashi M.,Japan National Institute of Materials Science | Yamanouchi M.,Tohoku University | And 4 more authors.
Nature Materials | Year: 2013

Current-induced effective magnetic fields can provide efficient ways of electrically manipulating the magnetization of ultrathin magnetic heterostructures. Two effects, known as the Rashba spin orbit field and the spin Hall spin torque, have been reported to be responsible for the generation of the effective field. However, a quantitative understanding of the effective field, including its direction with respect to the current flow, is lacking. Here we describe vector measurements of the current-induced effective field in Ta|CoFeB|MgO heterostructrures. The effective field exhibits a significant dependence on the Ta and CoFeB layer thicknesses. In particular, a 1 nm thickness variation of the Ta layer can change the magnitude of the effective field by nearly two orders of magnitude. Moreover, its sign changes when the Ta layer thickness is reduced, indicating that there are two competing effects contributing to it. Our results illustrate that the presence of atomically thin metals can profoundly change the landscape for controlling magnetic moments in magnetic heterostructures electrically. © 2013 Macmillan Publishers Limited. All rights reserved.


Khazaei M.,Japan National Institute of Materials Science | Arai M.,Japan National Institute of Materials Science | Sasaki T.,Japan National Institute of Materials Science | Chung C.-Y.,Tohoku University | And 4 more authors.
Advanced Functional Materials | Year: 2013

Layered MAX phases are exfoliated into 2D single layers and multilayers, so-called MXenes. Using first-principles calculations, the formation and electronic properties of various MXene systems, M2C (M = Sc, Ti, V, Cr, Zr, Nb, Ta) and M2N (M = Ti, Cr, Zr) with surfaces chemically functionalized by F, OH, and O groups, are examined. Upon appropriate surface functionalization, Sc2C, Ti2C, Zr2C, and Hf2C MXenes are expected to become semiconductors. It is also derived theoretically that functionalized Cr2C and Cr2N MXenes are magnetic. Thermoelectric calculations based on the Boltzmann theory imply that semiconducting MXenes attain very large Seebeck coefficients at low temperatures. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Furumi S.,Japan National Institute of Materials Science | Ichimura K.,Toho University
Physical Chemistry Chemical Physics | Year: 2011

Highly sensitive photoalignment of liquid crystals (LCs) can be realized by axis-selective triplet energy transfer. Addition of a triplet photosensitizer (phosphorescent donor) into a photocrosslinkable polymer tethering E-cinnamate side chains ensures dramatic enhancement of photosensitivity to generate the optical anisotropy of polymer film and surface-assisted LC photoalignment. Photoirradiation of triplet photosensitizer-doped polymer films with linearly polarized 365 nm light for the selective excitation of triplet sensitizer gives rise to optical anisotropy of cinnamates as a result of axis-selective triplet energy transfer. By analyzing phosphorescence spectra with theoretical Perrin's formula, we find that triplet energy transfer is efficient within a radius of ∼0.3 nm from the triplet photosensitizer. Such photoaligned polymer films can be used for the surface-assisted orientation photocontrol of not only calamitic LC, but also discotic LC, even for extremely low exposure energies. The present procedure would be greatly advantageous for high-throughput fabrication of optical devices by photoalignment techniques. © the Owner Societies 2011.


Spevacek J.,Czech Institute of Macromolecular Chemical | Hanykova L.,Charles University | Labuta J.,Japan National Institute of Materials Science
Macromolecules | Year: 2011

The behavior of water during the temperature-induced phase separation in PVME/D2O solutions was investigated by 1H NMR methods and optical microscopy. A fast exchange between water (HDO) bound in mesoglobules and free water was found from 1H NMR spin-spin relaxation measurements at temperature above the LCST transition for semidilute PVME/D 2O solutions where the exchange time is 1.2 ms for c = 6 wt %. In contrast, there is a slow exchange between bound and free water in highly concentrated PVME solutions and the residence time of the bound water 2 s was found for concentrations c = 20-50 wt % using one-dimensional NOE 1H NMR experiment. A 3 order of magnitude slower exchange in highly concentrated PVME/D2O solutions is in accord with our optical microscopy findings that globular-like structures are here approximately 20 times larger than in PVME solution with c = 6 wt %. © 2011 American Chemical Society.


Lu C.-P.,Rutgers University | Lu C.-P.,National Taiwan University | Li G.,Rutgers University | Watanabe K.,Japan National Institute of Materials Science | And 2 more authors.
Physical Review Letters | Year: 2014

One of the enduring challenges in graphene research and applications is the extreme sensitivity of its charge carriers to external perturbations, especially those introduced by the substrate. The best available substrates to date, graphite and hexagonal boron nitride (h-BN), still pose limitations: graphite being metallic does not allow gating, while both h-BN and graphite, having lattice structures closely matched to that of graphene, may cause significant band structure reconstruction. Here we show that the atomically smooth surface of exfoliated MoS2 provides access to the intrinsic electronic structure of graphene without these drawbacks. Using scanning tunneling microscopy and Landau-level (LL) spectroscopy in a device configuration that allows tuning of the carrier concentration, we find that graphene on MoS2 is ultraflat, producing long mean free paths, while avoiding band structure reconstruction. Importantly, the screening of the MoS2 substrate can be tuned by changing the position of the Fermi energy with relatively low gate voltages. We show that shifting the Fermi energy from the gap to the edge of the conduction band gives rise to enhanced screening and to a substantial increase in the mean free path and quasiparticle lifetime. MoS2 substrates thus provide unique opportunities to access the intrinsic electronic properties of graphene and to study in situ the effects of screening on electron-electron interactions and transport. © 2014 American Physical Society.


Martin-Olmos C.,University of California at Los Angeles | Rasool H.I.,University of California at Los Angeles | Rasool H.I.,Japan National Institute of Materials Science | Weiller B.H.,The Aerospace Corporation | And 2 more authors.
ACS Nano | Year: 2013

We explore the feasibility of growing a continuous layer of graphene in prepatterned substrates, like an engineered silicon wafer, and we apply this as a mold for the fabrication of AFM probes. This fabrication method proves the fabrication of SU-8 devices coated with graphene in a full-wafer parallel technology and with high yield. It also demonstrates that graphene coating enhances the functionality of SU-8 probes, turning them conductive and more resistant to wear. Furthermore, it opens new experimental possibilities such as studying graphene-graphene interaction at the nanoscale with the precision of an AFM or the exploration of properties in nonplanar graphene layers. © 2013 American Chemical Society.


Bejas M.,Abdus Salam International Center For Theoretical Physics | Greco A.,CONICET | Yamase H.,Japan National Institute of Materials Science | Yamase H.,Max Planck Institute for Solid State Research
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

Motivated by the growing evidence of the importance of charge fluctuations in the pseudogap phase in high-temperature cuprate superconductors, we apply a large-N expansion formulated in a path integral representation of the two-dimensional t-J model on a square lattice. We study all possible charge instabilities of the paramagnetic state in leading order of the 1/N expansion. While the d-wave charge density wave (flux phase) becomes the leading instability for various choices of model parameters, we find that a d-wave Pomeranchuk (electronic nematic phase) instability occurs as a next leading one. In particular, the nematic state has a strong tendency to become inhomogeneous. In the presence of a large second nearest-neighbor hopping integral, the flux phase is suppressed and the electronic nematic instability becomes leading in a high doping region. Besides these two major instabilities, bond-order phases occur as weaker instabilities close to half-filling. Phase separation is also detected in a finite temperature region near half-filling. © 2012 American Physical Society.


Wu K.C.-W.,National Taiwan University | Wu K.C.-W.,National Health Research Institute | Yamauchi Y.,Japan National Institute of Materials Science | Yamauchi Y.,Waseda University | Yamauchi Y.,Japan Science and Technology Agency
Journal of Materials Chemistry | Year: 2012

Mesoporous silica nanoparticles (MSNs) with particle sizes less than 100 nm and desired properties have been synthesized using various methods for several promising applications in the fields of biomedicine and catalysis. In this Highlight article, we briefly review the recent advances in this emerging nanomaterial. Some general aspects including control of particle size, mesostructure and morphology, mechanism of formation, and future challenges are introduced and discussed. © The Royal Society of Chemistry 2012.


Hayashi M.,Japan National Institute of Materials Science | Kim J.,Japan National Institute of Materials Science | Yamanouchi M.,Tohoku University | Ohno H.,Tohoku University
Physical Review B - Condensed Matter and Materials Physics | Year: 2014

Solid understanding of current induced torques is a key to the development of current and voltage controlled magnetization dynamics in ultrathin magnetic heterostructures. To evaluate the size and direction of such torques, or effective fields, a number of methods have been employed. Here, we examine the adiabatic (low-frequency) harmonic Hall voltage measurement that has been used to study the effective field. We derive an analytical formula for the harmonic Hall voltages to evaluate the effective field for both out of plane and in-plane magnetized systems. The formula agrees with numerical calculations based on a macrospin model. Two different in-plane magnetized films, Pt|CoFeB|MgO and CuIr|CoFeB|MgO are studied using the formula developed. The effective field obtained for the latter system shows relatively good agreement with that estimated using spin torque switching phase diagram measurements reported previously. Our results illustrate the versatile applicability of harmonic Hall voltage measurement for studying current induced torques in magnetic heterostructures. © 2014 American Physical Society.


Kuo I.-J.,National Taiwan University | Suzuki N.,Japan National Institute of Materials Science | Yamauchi Y.,Japan National Institute of Materials Science | Wu K.C.-W.,National Taiwan University
RSC Advances | Year: 2013

Mesoporous titania and zirconia nanoparticles (MTN and MZrN, respectively) exhibiting a desired specific surface area and porous structure, different acidity, and different crystallinity were successfully synthesized through a controlled hydrolysis method and different post-treatments without the utilization of surfactants. The catalytic activities of the synthesized MTN and MZrN were investigated for the conversion of cellulose to glucose and 5-hydroxymethylfurfural (HMF) in an ionic liquid (i.e., 1-ethyl-3- methylimidazolium chloride, [EMIM]Cl) system. The amount of the catalyst (4.0 mg) and reaction time (3 h) were optimized for cellulosic conversion over the HT-MTN catalyst, resulting in maximum 12.9% glucose and 18.2% HMF yields at 120 °C reaction temperature. HT-MZrN exhibited superior HMF yield (i.e., 29.2%) to HT-MTN (i.e., 18.2%) because of the appearance of relatively strong acidity at 450 °C. In addition, we studied the effect of different crystallinity (i.e., amorphous, tetragonal, and monoclinic phases) of the same MZrN material on the conversion yields of glucose and HMF. Crystalline MZrN materials (i.e., either tetragonal or monoclinic phase) exhibited higher HMF yields than amorphous MZrN because of the existence of relatively strong acidity. The tetragonal MZrN catalyst presented better performance than monoclinic and amorphous MZrN catalysts because its acidity at higher temperature (i.e., over 450 °C) was higher than that of the other two, which shows great potential in one-pot cellulose-to-HMF conversion. © 2012 The Royal Society of Chemistry.


Salunkhe R.R.,Japan National Institute of Materials Science | Hsu S.-H.,National Taiwan University | Wu K.C.W.,National Taiwan University | Yamauchi Y.,Japan National Institute of Materials Science
ChemSusChem | Year: 2014

We report an effective route for the preparation of layered reduced graphene oxide (rGO) with uniformly coated polyaniline (PANI) layers. These nanocomposites are synthesized by chemical oxidative polymerization of aniline monomer in the presence of layered rGO. SEM, TEM, X-ray photoelectron spectroscopy (XPS), FTIR, and Raman spectroscopy analysis results demonstrated that reduced graphene oxide-polyaniline (rGO-PANI) nanocomposites are successfully synthesized. Because of synergistic effects, rGO-PANI nanocomposites prepared by this approach exhibit excellent capacitive performance with a high specific capacitance of 286 F g-1 and high cycle reversibility of 94 % after 2000 cycles. Not just a flash in the PANI: An effective route for the preparation of layered reduced graphene oxide (rGO) with uniformly coated polyaniline (PANI) layers is reported. The nanocomposites are synthesized by chemical oxidative polymerization of aniline monomer in the presence of layered rGO. Through synergistic effects, the rGO-PANI nanocomposites exhibit excellent capacitive performance with a high specific capacitance and high cycle reversibility. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Estili M.,Japan National Institute of Materials Science | Sakka Y.,Japan National Institute of Materials Science | Kawasaki A.,Tohoku University
Nanotechnology | Year: 2013

Carbon nanotubes (CNTs) have a remarkable load-bearing ability. Recently, however, multi-walled CNTs (MWCNTs) have been shown to possess dramatically higher load-bearing ability when intimately embedded in an oxide ceramic (Al2O3), because the load could be transferred not to only their outermost walls but also their generally unloaded inner walls via the strong interwall shear resistance originating from residual compressive stresses. This phenomenon is characterized by an uncommon, highly energy-dissipating, multiwall-type failure of individual MWCNTs during hybrid fracture, with no evidence of pullout. Here, we demonstrate that this nanoscale in-MWCNT load-transfer process, at an optimized, high loading of MWCNTs (10 vol%) and in a pore-free and uniform platform, leads to unprecedented, dramatic simultaneous enhancement in strain tolerance (81%), fracture toughness (52.2%), and flexural strength (22%) of the Al2O3 ceramic matrix. The extent of toughening by this mechanism is also the highest ever reported. This unprecedented performance by using a high loading of functional MWCNTs, namely, toughening, strengthening, softening and lightening, simultaneously and at this level, has implications for many functional and structural applications. © 2013 IOP Publishing Ltd.


Acharya S.,Indian Association for The Cultivation of Science | Das B.,Indian Association for The Cultivation of Science | Thupakula U.,Indian Association for The Cultivation of Science | Ariga K.,Japan National Institute of Materials Science | And 3 more authors.
Nano Letters | Year: 2013

Two-dimensional (2D) sheets are currently in the spotlight of nanotechnology owing to high-performance device fabrication possibilities. Building a free-standing quantum sheet with controlled morphology is challenging when large planar geometry and ultranarrow thickness are simultaneously concerned. Coalescence of nanowires into large single-crystalline sheet is a promising approach leading to large, molecularly thick 2D sheets with controlled planar morphology. Here we report on a bottom-up approach to fabricate high-quality ultrathin 2D single crystalline sheets with well-defined rectangular morphology via collective coalescence of PbS nanowires. The ultrathin sheets are strictly rectangular with 1.8 nm thickness, 200-250 nm width, and 3-20 μm length. The sheets show high electrical conductivity at room and cryogenic temperatures upon device fabrication. Density functional theory (DFT) calculations reveal that a single row of delocalized orbitals of a nanowire is gradually converted into several parallel conduction channels upon sheet formation, which enable superior in-plane carrier conduction. © 2013 American Chemical Society.


Bochterle J.,Kirchhoff Institute for Physics | Neubrech F.,Kirchhoff Institute for Physics | Nagao T.,Japan National Institute of Materials Science | Pucci A.,Kirchhoff Institute for Physics
ACS Nano | Year: 2012

The resonantly enhanced near-field of micrometer-sized gold antennas has been probed with Angstrom-scale resolution. In situ surface-enhanced infrared spectroscopic vibrational signals of carbon monoxide (CO) layers cold-condensed on the antennas in ultrahigh-vacuum conditions are compared to the signals of CO layers with corresponding thicknesses on a flat gold surface. Vibrational signals of CO as well as the shift of the plasmonic resonance frequency were used to analyze the distance dependence of the near-field. The signal enhancement induced by the antennas not only decays monotonically from the surface but, in contrast to classical near-field models, shows a maximum between 10 and 15 Å and decays also toward the surface of the antenna. This effect is attributed to the spill-out of the electron wave function, as expected from quantum mechanical calculations. © 2012 American Chemical Society.


Nagura K.,Nagoya University | Saito S.,Nagoya University | Saito S.,Japan Science and Technology Agency | Yusa H.,Japan National Institute of Materials Science | And 5 more authors.
Journal of the American Chemical Society | Year: 2013

Luminescent mechanochromism has been intensively studied in the past few years. However, the difference in the anisotropic grinding and the isotropic compression is not clearly distinguished in many cases, in spite of the importance of this discrimination for the application of such mechanochromic materials. We now report the distinct luminescent responses of a new organic fluorophore, tetrathiazolylthiophene, to these stresses. The multichromism is achieved over the entire visible region using the single fluorophore. The different mechanisms of a blue shift by grinding crystals and of a red shift under hydrostatic pressure are fully investigated, which includes a high-pressure single-crystal X-ray diffraction analysis. The anisotropic and isotropic modes of mechanical loading suppress and enhance the excimer formation, respectively, in the 3D hydrogen-bond network. © 2013 American Chemical Society.


Hasegawa T.,Japan National Institute of Materials Science | Ohno T.,Japan National Institute of Materials Science | Terabe K.,Japan National Institute of Materials Science | Tsuruoka T.,Japan National Institute of Materials Science | And 3 more authors.
Advanced Materials | Year: 2010

(Fig. Represented) Learning abilities are demonstrated using a single solid-state atomic switch, wherein the formation and dissolution of a metal filament are controlled depending on the history of prior switching events. The strength of the memorization level gradually increases when the number of input signals is increased. Once the filament forms a bridge, electrons flow in a ballistic mode and long-term memorization is achieved (see figure). © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.


Cui C.Y.,CAS Shenyang Institute of Metal Research | Gu Y.F.,Japan National Institute of Materials Science | Yuan Y.,Japan National Institute of Materials Science | Harada H.,Japan National Institute of Materials Science
Scripta Materialia | Year: 2011

Dynamic strain aging (DSA) in a newly developed Ni-Co superalloy, TMW-2, was examined at temperatures ranging from room temperature to 600°C and strain rates between 3 × 10-2 and 8 × 10-5 s-1. The alloy exhibited both normal and inverse DSA effects at the temperatures and strain rates tested. Transmission electron microscopy evidence suggests that the normal behavior is associated with conventional DSA due to dynamic dislocation-solute interaction, while the inverse behavior may be related to the occurrence of stacking faults. © 2010 Published by Elsevier Ltd. on behalf of Acta Materialia Inc. All rights reserved.


Torrejon J.,Japan National Institute of Materials Science | Kim J.,Japan National Institute of Materials Science | Sinha J.,Japan National Institute of Materials Science | Mitani S.,Japan National Institute of Materials Science | And 3 more authors.
Nature Communications | Year: 2014

Recent advances in the understanding of spin orbital effects in ultrathin magnetic heterostructures have opened new paradigms to control magnetic moments electrically. The Dzyaloshinskii-Moriya interaction (DMI) is said to play a key role in forming a Néel-type domain wall that can be driven by the spin Hall torque. Here we show that the strength and sign of the DMI can be changed by modifying the adjacent heavy-metal underlayer (X) in perpendicularly magnetized X/CoFeB/MgO heterostructures. The sense of rotation of a domain wall spiral is reversed when the underlayer is changed from Hf, Ta to W and the strength of DMI varies as the filling of 5d orbitals, or the electronegativity, of the heavy-metal layer changes. The DMI can even be tuned by adding nitrogen to the underlayer, thus allowing interface engineering of the magnetic texture in ultrathin magnetic heterostructures. © 2014 Macmillan Publishers Limited. All rights reserved.


Patent
Murata Manufacturing Co. and Japan National Institute of Materials Science | Date: 2013-02-20

A piezoelectric ceramic having excellent electrical characteristics, and in which all of three crystallographic axes are oriented is obtained by slip cast or sheet forming a ceramic slurry containing plate-shaped ceramic particles in magnetic field. The degree of orientation of a first axis (for example, a c axis) calculated with the Lotgering method based on an X-ray diffraction (XRD) pattern in a prescribed cross-section of this piezoelectric ceramic is not less than 0.30. With a cross-section where the degree of orientation of the first axis indicates a maximum value being defined as a reference plane, the degree of orientation of a second axis (for example, an a axis) calculated with the Lotgering method based on an X-ray diffraction pattern in a cross-section orthogonal to this reference plane is not less than 0.20. The degree of orientation of the second axis is represented by a value in such a cross-section that the degree of orientation of the second axis attains to a maximum value, among cross-sections orthogonal to the reference plane.


Patent
Murata Manufacturing Co. and Japan National Institute of Materials Science | Date: 2014-10-22

Piezoelectric oriented ceramics containing a Pb(Ti, Zr)O_(3)-based compound as a compound having a perovskite structure and a method of manufacturing the same are provided. The piezoelectric oriented ceramics according to the present invention contains a Pb(Ti, Zr)O_(3)-based compound having a perovskite structure. This piezoelectric oriented ceramics has a high degree of orientation not lower than 0.64, which was calculated with the Lotgering method based on an X-ray diffraction pattern in a prescribed cross-section thereof, and has sintered density not lower than 85% of theoretical density.


Patent
Murata Manufacturing Co. and Japan National Institute of Materials Science | Date: 2014-08-13

resistance switching device having a high resistance variation ratio, an excellent response characteristic, an excellent resistance memory characteristic (retention characteristics) and an excellent repeat resistance. The resistance switching device comprises an n-type oxide semiconductor and first and second electrodes which are disposed so as to interpose at least a part of the n-type oxide semiconductor therebetween wherein a Schottky junction which provides resistance variation/memory characteristics by the application of voltage having different polarities between the first and second electrodes is formed at an interface between the n-type oxide semiconductor and the first electrode; and the first electrode is positioned such that it is in contact with the n-type oxide semiconductor, and has a lower layer which is formed from Au oxide or a Pt oxide or Au or Pt containing oxygen having the thickness of 1-50 nm.


Patent
Fujikura Ltd, Japan National Institute of Materials Science and Garcia | Date: 2013-02-27

The present invention provides a garnet single crystal comprising a terbium aluminum garnet single crystal, wherein a portion of the aluminum is substituted with scandium, and a portion of at least one of the aluminum and terbium is substituted with at least one type selected from the group consisting of thulium, ytterbium and yttrium.


Patent
Japan National Institute of Materials Science and Murata Manufacturing Co. | Date: 2013-10-10

A thin film capacitor includes a substrate and a dielectric thin film element formed on the substrate. The substrate can include an Si plate, an SiO_(2 )film on the Si plate, and a Ti film formed on the SiO_(2 )film. The dielectric thin film element includes a lower electrode, a dielectric thin film on the lower electrode, and an upper electrode formed on the dielectric thin film. The dielectric thin film is a thin film formed of a nanosheet, and a void portion of the dielectric thin film is filled with a p-type conductive organic polymer. Ti_(0.87)O_(2), Ca_(2)Nb_(3)O_(10 )or the like, is used as a dielectric material to form a major component of the nanosheet. As the p-type conductive organic polymer, polypyrrole, polyaniline, polyethylene dioxythiophene or the like, is suitable.


Patent
Murata Manufacturing Co. and Japan National Institute of Materials Science | Date: 2014-05-30

Piezoelectric oriented ceramics containing a Pb(Ti, Zr)O_(3)-based compound having a high degree of orientation not lower than 0.64, which was calculated with the Lotgering method based on an X-ray diffraction pattern in a prescribed cross-section thereof, and having a sintered density not lower than 85% of a theoretical density.


Yankowitz M.,University of Arizona | Xue J.,University of Arizona | Cormode D.,University of Arizona | Sanchez-Yamagishi J.D.,Massachusetts Institute of Technology | And 6 more authors.
Nature Physics | Year: 2012

The Schrödinger equation dictates that the propagation of nearly free electrons through a weak periodic potential results in the opening of bandgaps near points of the reciprocal lattice known as Brillouin zone boundaries 1. However, in the case of massless Dirac fermions, it has been predicted that the chirality of the charge carriers prevents the opening of a bandgap and instead new Dirac points appear in the electronic structure of the material 2,3. Graphene on hexagonal boron nitride exhibits a rotation-dependent moiré pattern 4,5. Here, we show experimentally and theoretically that this moiré pattern acts as a weak periodic potential and thereby leads to the emergence of a new set of Dirac points at an energy determined by its wavelength. The new massless Dirac fermions generated at these superlattice Dirac points are characterized by a significantly reduced Fermi velocity. Furthermore, the local density of states near these Dirac cones exhibits hexagonal modulation due to the influence of the periodic potential. © 2012 Macmillan Publishers Limited. All rights reserved.


Belik A.A.,Japan International Center for Materials Nanoarchitectonics | Matsushita Y.,Japan National Institute of Materials Science | Tanaka M.,Japan National Institute of Materials Science | Takayama-Muromachi E.,Japan National Institute of Materials Science
Chemistry of Materials | Year: 2012

ScCrO 3 and InCrO 3 were synthesized at high pressure of 6 GPa and 1500 K. Crystal structures of ScCrO 3 and InCrO 3 were studied with synchrotron X-ray powder diffraction. They crystallize in the GdFeO 3-type perovskite structure (space group Pnma, a = 5.35845(1) Å, b = 7.37523(1) Å, c = 5.03139(1) Å for ScCrO 3 and a = 5.35536(1) Å, b = 7.54439(1) Å, c = 5.16951(1) Å for InCrO 3). The physical properties of ScCrO 3 and InCrO 3 were investigated with specific heat, ac/dc magnetization, and dielectric measurements and compared with those of YCrO 3 with nonmagnetic Y 3+ ions at the A site. Antiferromagnetic transitions occur at T N = 73 K in ScCrO 3 and 93 K in InCrO 3 in agreement with the general trend of ACrO 3 (A = Y and rare earths) where T N decreases with decreasing the radius of the A ions. Extremely weak ferromagnetism was found in ScCrO 3 and InCrO 3 in contrast to YCrO 3. Ac magnetization measurements revealed some peculiarities in behavior of ScCrO 3 and InCrO 3, namely, double-peak anomalies just below T N. Dielectric anomalies were observed in both compounds at T N indicating magnetoelectric coupling in contact with YCrO 3 where no dielectric anomalies were found. ScCrO 3 and InCrO 3 are very stable for high-pressure phases: no decomposition of ScCrO 3 was observed after heating up to 1340 K in air, and InCrO 3 only partially decomposed at 1340 K to give Cr 2O 3 and ambient- and high-pressure modifications of In 2O 3 as impurities. No anomalies were also found with differential scanning calorimetry up to 870 K and differential thermal analysis up to 1340 K, indicating the absence of high-temperature phase transitions. © 2012 American Chemical Society.


Belik A.A.,Japan International Center for Materials Nanoarchitectonics | Rusakov D.A.,Japan International Center for Materials Nanoarchitectonics | Furubayashi T.,Japan National Institute of Materials Science | Takayama-Muromachi E.,Japan National Institute of Materials Science
Chemistry of Materials | Year: 2012

Solid solutions of BiGa xM 1-xO 3 (M = Cr, Mn, and Fe) were prepared using the high-pressure high-temperature method at 6 GPa and 1700 K (M = Cr and Fe) and 1300 K (M = Mn). The formation of a large family of polar materials with R3c and Cm symmetries was found. Crystal structures were studied with laboratory X-ray powder diffraction: space group Cm, a = 5.3150(1) Å, b = 5.2960(1) Å, c = 4.6965(1) Å, and β = 92.556(2)° for BiGa 0.4Fe 0.6O 3; space group Cm, a = 5.2798(1) Å, b = 5.2577(1) Å, c = 4.6465(1) Å, and β = 91.974(2)° for BiGa 0.7Mn 0.3O 3; space group R3c, a = 5.51623(8) Å and c = 13.61391(17) Å for BiGa 0.4Cr 0.6O 3. Samples with the Cm symmetry have square-pyramidal coordination of (Ga,M) 3+ ions, and their structure is very similar with the structure of supertetragonal PbVO 3, BiCoO 3, and Bi 2ZnTiO 6 materials. Samples with the R3c symmetry are isostructural with BiFeO 3 and have comparable calculated (based on the point-charge model) spontaneous polarization (58 μC/cm 2 for BiGa 0.4Cr 0.6O 3). The calculated polarization is 116 μC/cm 2 for BiGa 0.4Fe 0.6O 3, and 102 μC/cm 2 for BiGa 0.7Mn 0.3O 3. BiGa 0.4Cr 0.6O 3 has a first-order structural phase transition at 850 K, and other polar samples showed no phase transitions below decomposition temperatures. The BiGa xMn 1-xO 3 system demonstrated strong phase competition at 0.6 ≤ x ≤ 2/3. © 2012 American Chemical Society.


Tominaka S.,Japan International Center for Materials Nanoarchitectonics | Tsujimoto Y.,Japan National Institute of Materials Science | Matsushita Y.,NIMS Beamline Station at SPring 8 | Yamaura K.,Japan National Institute of Materials Science
Angewandte Chemie - International Edition | Year: 2011

Reduction without particle growth: Ti 2O 3 nanoparticles of corundum structure were synthesized by reducing TiO 2 nanoparticles of rutile structure with CaH 2 powder at a low temperature of 350 °C. The morphology of the reduced oxide was the same as that of the precursor, though the crystal structure was transformed from the tetragonal to the hexagonal system (see picture). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Tomozawa M.,Japan National Institute of Materials Science | Hiromoto S.,Japan National Institute of Materials Science | Hiromoto S.,Japan International Center for Materials Nanoarchitectonics
Applied Surface Science | Year: 2011

Hydroxyapatite (HAp) coatings were uniformly formed on pure Mg by a hydrothermal treatment using a C 10H 12N 2O 8Na 2Ca (Ca-EDTA) solution. The growth mechanism of the HAp coating was investigated with XRD, SEM and TEM. At the initial stage, dome-shape HAp precipitates were formed on the Mg. Subsequently, the precipitates grew and the coating became a dual-layer consisting of an inner dense HAp layer and outer course layer consisting of rod-like HAp crystals. The protectiveness of the coatings with different treatment times was investigated by a polarization test in a 3.5 wt.% NaCl solution. The corrosion current density decreased with the growth of the HAp coating. © 2011 Elsevier B.V. All rights reserved.


Tomozawa M.,Japan National Institute of Materials Science | Hiromoto S.,Japan National Institute of Materials Science | Hiromoto S.,Japan International Center for Materials Nanoarchitectonics
Acta Materialia | Year: 2011

Hydroxyapatite (HAp) coatings with and without octacalcium phosphate (OCP) were uniformly formed on pure magnesium by a hydrothermal treatment using a Ca-EDTA solution. The crystal structure, crystallographic orientation and lattice images were investigated using transmission electron microscopy (TEM) and high-resolution TEM. It was demonstrated that the crystal phase and microstructure of the calcium phosphate-coatings can vary with the pH of the treatment solution. In a weak acid treatment solution, a dual-layer structure was formed: an outer coarse layer consisting of plate-like OCP crystals and an inner dense layer consisting primarily of HAp crystals. One piece of the OCP plate corresponded to a single OCP crystal growing parallel to the (1 0 0) OCP. In a weak alkali treatment solution, a dual-layer structure was also formed: an outer coarse layer consisting of rod-like HAp crystals and an inner dense layer consisting of HAp crystals. One piece of the HAp rod corresponded to a single HAp crystal growing along [0 0 2]HAp. In a strong alkali treatment solution, needle-like HAp crystals were formed. No defect was observed in the lattice image of the OCP and HAp. The corrosion current density of pure magnesium in a 3.5 wt.% NaCl solution decreased with the HAp coating more significantly than the OCP + HAp coating. It is revealed that the degree of protection afforded by calcium phosphate-coatings varies with their crystal phase and microstructure. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Tong H.,Japan International Center for Materials Nanoarchitectonics | Ouyang S.,Japan National Institute of Materials Science | Bi Y.,Japan International Center for Materials Nanoarchitectonics | Umezawa N.,Japan National Institute of Materials Science | And 4 more authors.
Advanced Materials | Year: 2012

Semiconductor photocatalysis has received much attention as a potential solution to the worldwide energy shortage and for counteracting environmental degradation. This article reviews state-of-the-art research activities in the field, focusing on the scientific and technological possibilities offered by photocatalytic materials. We begin with a survey of efforts to explore suitable materials and to optimize their energy band configurations for specific applications. We then examine the design and fabrication of advanced photocatalytic materials in the framework of nanotechnology. Many of the most recent advances in photocatalysis have been realized by selective control of the morphology of nanomaterials or by utilizing the collective properties of nano-assembly systems. Finally, we discuss the current theoretical understanding of key aspects of photocatalytic materials. This review also highlights crucial issues that should be addressed in future research activities. The state-of-the-art research activities in the field of photocatalysis is reviewed to reveal the key issues, challenges, and opportunities facing present and future research on photocatalytic materials. Energy band engineering, nanotechnology, modern materials characterization methods and advanced theoretical studies promise to sustain rapid development of photocatalytic materials to contribute an encouraging prospect in the realization of a sustainable society. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Xu M.,Japan National Institute of Materials Science | Xu M.,Zhejiang University | Fujita D.,Japan International Center for Materials Nanoarchitectonics | Gao J.,Japan International Center for Materials Nanoarchitectonics | Hanagata N.,Japan National Institute of Materials Science
ACS Nano | Year: 2010

We report the determination of the thickness of graphene layers by Auger electron spectroscopy (AES). We measure AES spectra of graphenes with different numbers of layers. The AES spectroscopy shows distinct spectrum shape, intensity, and energy characteristics with an increasing number of graphene layers. We also calculate electron inelastic mean free paths for graphene layers directly from these measurements. The method allows unambiguous and high-throughput determination of thickness up to six graphene layers and detection of defect and dopant in graphene films on almost any substrate. The availability of this reliable method will permit direct probing of graphene growth mechanisms and exploration of novel properties of graphenes with different thicknesses on diverse substrates. © 2010 American Chemical Society.


Aikawa S.,Japan International Center for Materials Nanoarchitectonics | Nabatame T.,Japan National Institute of Materials Science | Tsukagoshi K.,Japan International Center for Materials Nanoarchitectonics
Applied Physics Letters | Year: 2013

Amorphous metal oxide thin-film transistors (TFTs) are fabricated using InOx-based semiconductors doped with TiO2, WO3, or SiO2. Even at low-dopant densities, the electrical properties of the film strongly depend on the dopant used. We found that this dependence could be reasonably explained by differences in the bond-dissociation energy of the dopants. By incorporating a dopant with a higher bond-dissociation energy, the film became less sensitive to the partial pressure of oxygen used during sputtering and remained electrically stable upon thermal annealing. Thus, choosing a dopant with an appropriate bond-dissociation energy is important when fabricating stable metal-oxide TFTs for flat-panel displays. © 2013 AIP Publishing LLC.


Seino Y.,Idemitsu Kosan Co. | Ota T.,Idemitsu Kosan Co. | Takada K.,Japan National Institute of Materials Science
Journal of Power Sources | Year: 2011

Rate capability of LiNi 0.8Co 0.15Al 0.05O 2 in solid-state cells was investigated with 70Li 2S-30P 2S 5 glass-ceramics as a sulfide solid electrolyte. It showed higher rate capability than LiCoO 2; discharge capacity observed at a current density of 10 mA cm -2 was ca. 70 mAh g -1. Surface coating with Li 4Ti 5O 12 onto the LiNi 0.8Co 0.15Al 0.05O 2 particles further improved the high-rate performance to give ca. 110 mAh g -1. The rate capability promises to realize all-solid-state lithium secondary batteries with very high performance. © 2011 Elsevier B.V. All rights reserved.


Pan C.,Japan National Institute of Materials Science | Pan C.,University of Tsukuba | Sugiyasu K.,Japan National Institute of Materials Science | Wakayama Y.,Japan International Center for Materials Nanoarchitectonics | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2013

Molecular wires: Fluorescent conjugated polymers that are sheathed within their own cyclic side chains have been synthesized (see picture). Owing to the unique three-dimensional architecture, the polymers are light-emissive, even in the film state, miscible, allowing the combination of various fluorescence colors, and thermoformable, like conventional plastics. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Liu K.,Japan International Center for Materials Nanoarchitectonics | Sakurai M.,Japan International Center for Materials Nanoarchitectonics | Liao M.,Japan National Institute of Materials Science | Aono M.,Japan International Center for Materials Nanoarchitectonics
Journal of Physical Chemistry C | Year: 2010

ZnO nanowire photodetectors with and without Au nanoparticles have been fabricated and investigated. The dark current decreases by 2 orders of magnitude and the ratio of photo current to dark current increases after covering with Au nanoparticles. Meanwhile, the decorated Au nanoparticles can drastically improve the response speed of ZnO nanowire photodetectors. A physical model based on band energy theory was developed to illustrate the origin of the improvement of performance for ZnO nanowire photodetector attached with Au. Our work suggests that rational integration of ZnO wire and metal nanoparticles is a viable approach to improving the performance of ZnO nanowire photodetectors, which may help to advance optoelectronic devices.


Ambrosi A.,Japan National Institute of Materials Science | Sasaki T.,Nagoya University | Pumera M.,Japan National Institute of Materials Science | Pumera M.,Japan International Center for Materials Nanoarchitectonics
Chemistry - An Asian Journal | Year: 2010

Here, we demonstrate thatplatelet graphite nanofibers (PGNFs) exhibit fast heterogeneous electrontransfer rates for a wide variety of compounds such as FeCl3, ferrocyanide, dopamine, uric acid, ascorbic acid, and the reduced form of β-nicotinamide adenine dinucleotide. The electrochemical properties of PGNFs are superior to those of multiwalled carbon nanotubes (MWCNTs) or graphite microparticles (GMPs). Transmission electron microscopy and Raman spectroscopy reveal that this arises from the unique graphene sheet orientation of such platelet nanofibers, which accounts for their unparalleled high ratio of graphene edge planes versus basal planes. © 2010 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim.


Zhang Y.,Japan National Institute of Materials Science | Zhang Y.,Japan International Center for Materials Nanoarchitectonics | Mori T.,Japan National Institute of Materials Science | Ye J.,Japan International Center for Materials Nanoarchitectonics | And 2 more authors.
Journal of the American Chemical Society | Year: 2010

(Figure Presented) As a new kind of polymeric semiconductors, graphitic carbon nitride (g-C3N4) and its incompletely condensed precursors are stable up to 550 °C in air and have shown promising photovoltaic applications. However, for practical applications, their efficiency, limited e.g. by band gap absorption, needs further improvement. Here we report a "structural doping" strategy, in which phosphorus heteroatoms were doped into g-C3N4 via carbon sites by polycondensation of the mixture of the carbon nitride precursors and phosphorus source (specifically from 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid). Most of the structural features of g-C3N4 were well retained after doping, but electronic features had been seriously altered, which provided not only a much better electrical (dark) conductivity up to 4 orders of magnitude but also an improvement in photocurrent generation by a factor of up to 5. In addition to being active layers in solar cells, such phosphorus-containing scaffolds and materials are also interesting for polymeric batteries as well as for catalysis and as catalytic supports. © 2010 American Chemical Society.


Tabuchi M.,Japan National Institute of Materials Science | Takahashi Y.,Japan Central Research Institute of Electric Power Industry
Journal of Pressure Vessel Technology, Transactions of the ASME | Year: 2012

Creep strength of welded joint for high Cr ferritic heat resisting steels decreases due to Type-IV failure in heat-affected zone (HAZ) during long-term use at high temperatures. In order to review the allowable creep strength of these steels, creep rupture data of base metals and welded joints have been collected, and long-term creep strength has been evaluated in the SHC (strength of high-chromium steel) committee in Japan. In the present paper, the creep rupture data of 370 points for welded joint specimens of modified 9Cr-1Mo steel (ASME Grade 91 steel) offered from seven Japanese companies and institutes were analyzed. These data clearly indicated that the creep strength of welded joints was lower than that of base metal due to Type-IV failure in HAZ at high temperatures. From the activities of this committee, it was concluded that the weld strength reduction factor (WSRF) should be taken into consideration for the design and residual life assessment of boiler components in fossil power plants. The committee recommended the WSRF for 100,000 h creep of Gr.91 steel as 0.85 at 575 °C, 0.75 at 600 °C, 0.74 at 625 °C, and 0.70 at 650 °C. The master curve for residual life assessment of Gr.91 steel welds using Larson-Miller parameter was also proposed. © 2012 American Society of Mechanical Engineers.


Van Mechelen J.L.M.,University of Geneva | Van Der Marel D.,University of Geneva | Crassee I.,University of Geneva | Kolodiazhnyi T.,Japan National Institute of Materials Science
Physical Review Letters | Year: 2011

We show an example of a purely magnetic spin resonance in EuTiO3 and the resulting new record high Faraday rotation of 590°/mm at 1.6 T for 1 cm wavelengths probed by a novel technique of magneto-optical gigahertz time-domain ellipsometry. From our transmission measurements of linear polarized light, we map out the complex index of refraction n=μ in the gigahertz to terahertz range. We observe a strong resonant absorption by magnetic dipole transitions involving the Zeeman split S=7/2 magnetic energy levels of the Eu2+ ions, which causes a very large dichroism for circular polarized radiation. © 2011 American Physical Society.


Goda T.,Japan National Institute of Materials Science | Miyahara Y.,Japan National Institute of Materials Science | Miyahara Y.,Japan International Center for Materials Nanoarchitectonics
Analytical Chemistry | Year: 2010

Nonspecific protein adsorption on self-assembled monolayer (SAM) alkanethiols with various terminal groups was investigated qualitatively and quantitatively using an extended gate-field effect transistor (extended gate-FET). The SAMs were characterized by XPS, cyclic voltammogram and water contact angle measurements. Changes in gate voltage of 1 mV caused by intrinsic charges of adsorbed protein on an undecanethiol SAM in 15 mM Dulbecco's phosphate buffered saline were equivalent to 3.6 ng cm-2, 1.3 ng cm-2, and 16 ng cm-2 for bovine serum albumin (BSA), lysozyme, and bovine plasma fibrinogen (BPF), respectively, as calculated by the Debye - Huckel model. Adsorption coefficients, maximum adsorption densities, and Gibbs free energies of adsorption were successfully determined using the Langmuir equation. The isotherms depended on the surface properties of the SAMs for BSA and lysozyme adsorption. In contrast, changes in gate voltage were almost independent of SAM type for BPF adsorption. Adsorption of large proteins may not be quantitatively detected because of the large dimensions of the biomolecules compared with the Debye length. In summary, the FET measurement is a nonlabeling, highly sensitive, and quantitative method for detecting nonspecific adsorption of small proteins with dimensions that are comparable to the Debye length of a solution. © 2010 American Chemical Society.


Hiromoto S.,Japan National Institute of Materials Science | Hiromoto S.,Japan International Center for Materials Nanoarchitectonics | Tomozawa M.,Japan National Institute of Materials Science
Surface and Coatings Technology | Year: 2011

Hydroxyapatite (HAp) coatings were formed directly on AZ31 magnesium alloy and pure Mg in a 250mmol/L C10H12N2O8Na2Ca aqueous solution of pH 8.9. Treatment time was varied from 2h to 6h. Crystal phase, morphology and composition of the coatings were investigated. Immersion and polarization tests in a 3.5wt.% NaCl solution were performed to examine the corrosion behavior of the HAp-coated specimens. The HAp coating of AZ31 with short treatment time had defects which decreased with an increase in treatment time. The HAp coatings of AZ31 consisted of an inner dense layer and an outer coarse layer in the similar manner for pure Mg. The inner layer on AZ31 was composed of dome-shape precipitates densely packed. The outer layer was composed of rod-like crystals growing from each dome in the radial direction. The (002) plane of HAp of inner layer and rod-like crystals roughly oriented to the substrate. Magnesium ion-release and corrosion current density were remarkably reduced with HAp coatings. Each of these values was on the same order of magnitude between HAp-coated AZ31 and pure Mg. The ion release from AZ31 slightly decreased with an increase in treatment time. The original inner dense layer of AZ31 remained after the immersion. It is suggested that the protectiveness of HAp coating relays on the inner layer and does not significantly depend on the kind of Mg substrate. © 2011 Elsevier B.V.


Schnepp Z.,Japan National Institute of Materials Science | Schnepp Z.,University of Birmingham
Angewandte Chemie - International Edition | Year: 2013

Biomass is an abundant source of chemically diverse macromolecules, including polysaccharides, polypeptides, and polyaromatics. Many of these biological polymers (biopolymers) are highly evolved for specific functions through optimized chain length, functionalization, and monomer sequence. As biopolymers are a chemical resource, much current effort is focused on the breakdown of these molecules into fuels or platform chemicals. However there is growing interest in using biopolymers directly to create functional materials. This Minireview uses recent examples to show how biopolymers are providing new directions in the synthesis of nanostructured materials. Biomass is an abundant source of chemically diverse macromolecules. Much current effort is focused on the breakdown of these molecules into fuels or platform molecules. However, there is growing interest in using biopolymers directly to create nanostructured materials. It is highlighted how biopolymers are providing new directions in the synthesis of nanostructured materials. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Umezawa N.,Japan National Institute of Materials Science | Shuxin O.,Japan National Institute of Materials Science | Ye J.,Japan National Institute of Materials Science | Ye J.,Japan International Center for Materials Nanoarchitectonics
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The recent discovery of an excellent photocatalyst, Ag3PO 4, motivated us to clarify the origin of its high performance. Our comprehensive study using density-functional-theory-based calculations has revealed that the formation of PO4 tetrahedral units with strong P-O bonds weakens the covalent nature of Ag-O bonds, inhibiting hybridization of Ag d and O p. This excludes the d character from the conduction-band minimum (CBM), leaving highly dispersive Ag s-Ag s hybrid bands. The delocalized charge distribution of the CBM results in a small effective mass of the electron, which is advantageous for the carrier transfer to surface. © 2011 American Physical Society.


Imura K.-I.,Hiroshima University | Takane Y.,Hiroshima University | Tanaka A.,Japan National Institute of Materials Science
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

Three-dimensional topological insulators are characterized by the presence of protected gapless spin helical surface states. In realistic samples these surface states are extended from one surface to another, covering the entire sample. Generally, on a curved surface of a topological insulator an electron in a surface state acquires a spin Berry phase as an expression of the constraint that the effective surface spin must follow the tangential surface of real space geometry. Such a Berry phase adds up to π when the electron encircles, e.g., once around a cylinder. Realistic topological insulators compounds are also often layered, i.e., are anisotropic. We demonstrate explicitly the existence of such a π Berry phase in the presence and absence (due to crystal anisotropy) of cylindrical symmetry, that is, regardless of fulfilling the spin-to-surface locking condition. The robustness of the spin Berry phase π against cylindrical symmetry breaking is confirmed numerically using a tight-binding model implementation of a topological insulator nanowire penetrated by a π-flux tube. © 2011 American Physical Society.


Zhi C.,Japan International Center for Materials Nanoarchitectonics | Xu Y.,Japan National Institute of Materials Science | Bando Y.,Japan International Center for Materials Nanoarchitectonics | Golberg D.,Japan International Center for Materials Nanoarchitectonics
ACS Nano | Year: 2011

We report for the first time how boron nitride (BN) nanotubes and nanospheres may effectively be used to achieve remarkable thermal conductivity improvement of a fluid. Benefiting from high thermal conductivity and high-aspect-ratio of BN nanotubes, at a fraction of 6 vol %, the thermal conductivity of water was remarkably improved, up to ∼2.6-times. With BN nanospheres as fillers, the viscosity of the fluid can be kept decently low and thermal conductivity can also be effectively improved. A combination of BN nanotubes and nanospheres was found to increase the fluid's thermal conductivity while keeping its viscosity low, thus, such mixtures can be promising fillers for highly thermo-conductive fluids. Finally, calculations based on finite element method were used to investigate the regarded nanofluids. On the basis of the results, thermal conductivity was estimated to be more than, or close to 200 W/mK for BN nanotubes and nanospheres, respectively. © 2011 American Chemical Society.


Wakabayashi D.,University of Tokyo | Funamori N.,University of Tokyo | Sato T.,Hiroshima University | Taniguchi T.,Japan National Institute of Materials Science
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The compression behavior of fully densified SiO2 glass has been measured up to 9 GPa at room temperature by using a diamond-anvil cell with a mixture of methanol-ethanol as a pressure medium. Optical-microscope observations clarify that there is remarkable agreement between the volume data on compression and decompression and therefore the glass behaves in an elastic manner. The compression curve can be expressed accurately enough by a Birch-Murnaghan equation of state with the zero-pressure bulk modulus K 0 = 60.2 GPa and its pressure derivative K0′ = 4 (fixed). Extrapolating this equation of state to higher pressures, the density of the glass merges with that of ordinary glass (i.e., former ordinary glass compressed to high pressures) at about 13 GPa. X-ray diffraction and Raman scattering measurements show that the first sharp diffraction peak and the main Raman band of the glass also merge with those of ordinary glass at the similar pressure range. These results suggest that the compaction of interstitial voids dominates in compression mechanisms of densified SiO2 glass, similar to the case for ordinary SiO2 glass. Together with available information from the literature, it is presumed that the permanent densification of SiO 2 glass takes place between 9 and 13 GPa at room temperature. The behavior of SiO2 glass in its intermediately densified states is also discussed. © 2011 American Physical Society.


Belik A.A.,Japan International Center for Materials Nanoarchitectonics | Furubayashi T.,Japan National Institute of Materials Science | Yusa H.,Japan National Institute of Materials Science | Takayama-Muromachi E.,Japan International Center for Materials Nanoarchitectonics
Journal of the American Chemical Society | Year: 2011

LiNbO3 (LN), corundum (cor), and hexagonal (hex) phases of (In1-xMx)MO3 (x = 0.143; M = Fe 0.5Mn0.5) were prepared. Their crystal structures were investigated with synchrotron X-ray powder diffraction, and their properties were studied by differential thermal analysis, magnetic measurements, and Mössbauer spectroscopy. The LN-phase was prepared at high pressure of 6 GPa and 1770 K; it crystallizes in space group R3c with a = 5.25054(7) Å, c = 13.96084(17) Å, and has a long-range antiferromagnetic ordering near TN = 270 K. The cor- and hex-phases were obtained at ambient pressure by heating the LN-phase in air up to 870 and 1220 K, respectively. The cor-phase crystallizes in space group R-3c with a = 5.25047(10) Å, c = 14.0750(2) Å, and the hex-phase in space group P63/mmc with a = 3.34340(18) Å, c = 11.8734(5) Å. TN of the cor-phase is about 200 K, and TN of the hex-phase is about 140 K. During irreversible transformations of LN-(In1-xMx)MO3 with the (partial) cation ordering, the In3+, Mn3+, and Fe3+ cations become completely disordered in one crystallographic site of the corundum structure, and then they are (partially) ordered again in the hex-phase. LN-(In1-xMx)MO3 exhibits a reversible transformation to a perovskite GdFeO3-type structure (space group Pnma; a = 5.2946(3) Å, b = 7.5339(4) Å, c = 5.0739(2) Å at 10.3 GPa) at room temperature and pressure of about 5 GPa. © 2011 American Chemical Society.


Hiromoto S.,Japan International Center for Materials Nanoarchitectonics | Tomozawa M.,Japan National Institute of Materials Science | Maruyama N.,Japan International Center for Materials Nanoarchitectonics
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2013

A hydroxyapatite (HAp) coating was directly formed on an extruded AZ31 magnesium alloy by a single-step chemical solution deposition. The HAp coating consists of an outer porous HAp layer, an inner continuous HAp layer, and a thin intermediate MgO layer, and the inner HAp and MgO layers are composed of nanocrystals. Tensile and fatigue tests were performed on the HAp-coated AZ31 in air. The HAp coating microscopically showed neither crack nor detachment at 5% static elongation (1.5% residual strain). With further elongation under tensile stress, cracks were formed perpendicularly to the tensile direction, and fragments of the coating detached with a fracture inside the inner continuous HAp layer. The fatigue strengths at 107 cycles (fatigue limit) of HAp-coated and mechanically polished AZ31 were ca. 80MPa and ca. 90MPa, respectively. The slight decrease in the fatigue limit with the HAp coating is attributed to small pits with a depth of ca. 10μm formed on the substrate during the HAp-coating treatment. The HAp coating remained on the specimen without cracks after 107 cycles at the fatigue limit, which provides ca. 3% cyclic elongation. © 2013 Elsevier Ltd.


Ren X.,Xi'an University of Science and Technology | Ren X.,Japan National Institute of Materials Science
Physica Status Solidi (B) Basic Research | Year: 2014

The present article serves as a concise review of strain glass and its broader concept - ferroic glass. Strain glass is a frozen disordered strain state composed of nano-sized strain domains, which is formed due to the frustration created by point defects or dopants. Such frustration creates glassy nano-sized martensite-like domains that do not grow into a macroscopic martensite during cooling and instead show typical glass-freezing dynamics. Strain glass bears much resemblance with the glass phenomena found in other two types of ferroic systems, relaxor ferroelectric, and spin glass. These three ferroics-based glasses are thus called ferroic glasses. Characteristics of strain glass, including recent in situ high-resolution TEM images, are shown. Unusual properties associated with strain glass, such as superelasticity with narrow hysteresis, high-damping, and low modulus, as well as Invar and Elinvar effect in cold-rolled β-Ti alloys are demonstrated. Strain glass is a frozen disordered strain state composed of nano-sized strain domains, which is formed due to the frustration created by point defects or dopants. It bears much resemblance with the glass phenomena found in other two types of ferroic systems: relaxor ferroelectric and cluster spin glass. Unusual properties associated with strain glass, such as superelasticity with narrow hysteresis, high damping and low modulus, as well as Invar and Elinvar effect in cold-rolled β-Ti alloys are demonstrated. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ambrosi A.,Japan National Institute of Materials Science | Pumera M.,Japan National Institute of Materials Science | Pumera M.,Japan International Center for Materials Nanoarchitectonics
Chemistry - A European Journal | Year: 2010

In this article, we show that the redox properties of the regulatory peptide L-glutathione are affected by the presence of nickel oxide impurities within single-walled carbon nanotubes (SWCNTs). Glutathione is a powerful antioxidant that protects cells from oxidative stress by removing free radicals and peroxides. We show that the L-cysteine moiety in L-glutathione is responsible for the susceptibility to oxidation by metallic impurities present in the carbon nanotubes. These results have great significance for assessing the toxicity of carbon-nanotube materials. The SWCNTs were characterized by Raman spectroscopy, high-resolution X-ray photoelectron spectroscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy. © 2010 Wiley-VCH Verlag GmbH & Co. KGuA.


Wei X.,Japan National Institute of Materials Science | Wei X.,Japan International Center for Materials Nanoarchitectonics | Bando Y.,Japan International Center for Materials Nanoarchitectonics | Golberg D.,Japan International Center for Materials Nanoarchitectonics
ACS Nano | Year: 2012

Figure Persented: Electron emission from individual graphene nanoribbons (GNRs) driven by an internal electric field was studied for the first time inside a high resolution transmission electron microscope equipped with a state-of-art scanning tunneling microscope sample holder with independent twin probes. Electrons were driven out from individual GNRs under an internal driving voltage of less than 3 V with an emission current increasing exponentially with the driving voltage. The emission characteristics were analyzed by taking into account monatomic thickness of GNRs. While deviating from the two-dimensional Richardson equation for thermionic emission, they were well described by the recently proposed by us phonon-assisted electron emission model. Different from widely studied field electron emission from graphene edges, electrons were found to be emitted perpendicularly to the atomic graphene surfaces with an emission density as high as 12.7 A/cm 2. The internally driven electron emission is expected to be less sensitive to the microstructures of an emitter as compared to field emission. The low driving voltage, high emission density, and internal field driving character make the regarded electron emission highly promising for electron source applications. © 2011 American Chemical Society.


Patent
Japan National Institute of Materials Science and Nissin Giken Co. | Date: 2012-04-18

A heating section 20 having heating elements using carbon which generates heat when a high-frequency electric current is fed to a coil whose pitch can be adjusted as desired is arranged in a heating chamber 10. A cooling chamber 80 configured to cool metal to be heat-treated, which has been heated by the heating elements, is disposed below the heating chamber 10 in communication with the heating chamber 10 via a connection section 60. A water-cooled vertically movable shaft 90 which is capable of supporting the metal to be heat-treated and entering the heating chamber 10 is disposed so as to penetrate through the bottom portion of the cooling chamber 80. A gas introducing pipe 81 configured to introduce gas for cooling heated metal to be heat-treated supported by the water-cooled vertically movable shaft 90 and moved from the heating chamber 10 to the cooling chamber 80 is disposed in the cooling chamber 80, so that a heat treatment furnace which is capable of reducing running cost and increasing cooling speed is realized.


Patent
Japan National Institute of Materials Science, Takenaka Corporation and Awaji Materia Co. | Date: 2015-11-04

A damping alloy that is an Fe-Mn-(Cr, Ni)-Si-based damping alloy containing at least one of Cr or Ni or further contains Al, the damping alloy containing component compositions of:5 mass% Mn 28 mass%;0 mass% Cr 15 mass%;0 mass% Ni < 15 mass%;0 mass% < Si < 6.5 mass%; and0 mass% Al < 3 mass%,the balance being Fe and inevitable impurities,wherein the component compositions satisfy the following conditions:[%Ni] + 0.5 [%Mn] > 0.75 [%Cr] + 1.125 [%Si] + 2 [%Al]; and37 < [%Mn] + [%Cr] + 2 [%Ni] + 5 [%Al] < 45 (wherein [%Ni], [%Mn], [%Cr], [%Si], and [%Al] represent contents (mass%) of Ni, Mn, Cr, Si, and Al, respectively). Thus, a damping alloy for an elasto-plastic damper such as the Fe-Mn-(Cr, Ni)-Si-based alloy can be provided in which proof stress and stress amplitude after cyclic tension-compression deformation are lowered and the number of cycles to fracture is increased, the damping alloy being capable of being used in a maintenance-free manner even after long-period ground motion and being mass-produced.


Patent
Sharp Kabushiki Kaisha and Japan National Institute of Materials Science | Date: 2014-11-06

A wavelength conversion member includes a substrate and a fluorescent film that is disposed on the substrate and emits fluorescence upon reception of excitation light, wherein the fluorescent film includes an aggregate of a plurality of fluorescent particles, the aggregate being formed as a result of contact among the fluorescent particles, and a glass material filling gaps between the fluorescent particles in the aggregate, and a total volume of a volume of the glass material and a volume of the fluorescent particles in the fluorescent film is equal to or less than an envelope volume of the aggregate of the fluorescent particles in the fluorescent film.


Patent
Japan National Institute of Materials Science and Saint - Gobain | Date: 2012-04-26

A transparent electric conductor includes titanium oxide doped with aluminum and at least one other dopant: With the above composition, the electrical conductivity and the light transmittance are suitable for use of the transparent electric conductor in various applications, in particular as a transparent electrode of an electronic device.


Patent
Sumitomo Osaka Cement and Japan National Institute of Materials Science | Date: 2011-04-22

A method for forming a ferroelectric spontaneous polarization reversal includes the steps of forming a convexo-concave structure on a top face of a ferroelectric substrate firstly, and then forming a ferroelectric spontaneous polarization region on the substrate including one portion of a convex portion, with a concave portion being formed on the bottom face of the substrate within a region where a ferroelectric spontaneous polarization reversal is to be formed and the convex portion is formed, and then applying an electric field into the substrate. The depth of the concave portion on the bottom face of the substrate may be greater than the height of the convex portion on the top face of the substrate. The width of the concave portion on the bottom face of the substrate may be wider than width of said convex portion on the top face of the substrate.


Patent
Sharp Kabushiki Kaisha and Japan National Institute of Materials Science | Date: 2016-01-25

A wavelength converting member includes silica glass and a plurality of fluorescent material particles including an oxynitride or nitride fluorescent material and dispersed in the silica glass. The plurality of fluorescent material particles include at least two kinds of fluorescent material particles including (i) first fluorescent material particles that emit a fluorescence having a first peak wavelength and (ii) second fluorescent material particles that emit a fluorescence having a second peak wavelength. The wavelength converting member has a density within a range from 0.8 g/cm^(3 )to 1.2 g/cm^(3).


Patent
Sumitomo Osaka Cement and Japan National Institute of Materials Science | Date: 2011-04-22

A method for forming a ferroelectric spontaneous polarization reversal in a desired region of a ferroelectric substrate includes the steps of forming, for the desired region of the surface of the ferroelectric substrate, an electrode pattern or a mask pattern composed of aggregates of micropatterns, and then applying a given voltage into the desired region. The configuration of the micropatterns can be a stripe-shaped pattern, an ellipse-shaped pattern, a hexagon-shaped pattern, a network pattern, or a double cross shaped pattern. The method can further include the steps of generating many nucleuses by using the electrode pattern or the mask pattern composed of the aggregates of micropatterns, forming another electrode pattern or another mask pattern corresponding to the desired region, and then applying a given voltage into the desired region to generate a ferroelectric spontaneous polarization reversal around the nucleuses.


Patent
Sharp Kabushiki Kaisha and Japan National Institute of Materials Science | Date: 2015-08-05

A wavelength conversion member includes a substrate and a fluorescent film that is disposed on the substrate and emits fluorescence upon reception of excitation light, wherein the fluorescent film includes an aggregate of a plurality of fluorescent particles, the aggregate being formed as a result of contact among the fluorescent particles, and a glass material filling gaps between the fluorescent particles in the aggregate, and a total volume of a volume of the glass material and a volume of the fluorescent particles in the fluorescent film is equal to or less than an envelope volume of the aggregate of the fluorescent particles in the fluorescent film.


Patent
Sumitomo Osaka Cement and Japan National Institute of Materials Science | Date: 2011-04-22

A method for forming a ferroelectric spontaneous polarization reversal, including the steps of forming a concave portion on a top face of a ferroelectric substrate or a bottom face of a ferroelectric substrate, and applying an electric field into the substrate, wherein a ferroelectric spontaneous polarization reversal is formed at least in one portion of a region of the substrate with the concave portion, and wherein the shape of the concave portion is configured such that the width of the concave portion gets narrower gradually toward the inside of the substrate. The method may further include the steps of, after the reversal, making into almost a flat-plane the top or bottom face having the concave portion, and then, forming a new concave portion in another region and applying an electric field to form another reversal in one portion of the region of the substrate having the new concave portion.


Patent
Sharp Kabushiki Kaisha and Japan National Institute of Materials Science | Date: 2013-01-02

Disclosed is a light-emitting device that exhibits good color rendering and highly efficiently emits white light in an incandescent bulb color range. The semiconductor light-emitting device (1) of the present invention includes: a semiconductor light-emitting element (2) that emits blue light; a green phosphor (14) that absorbs the blue light and emits green light; and an orange phosphor (13) that absorbs the blue light and emits orange light. The orange phosphor (13) produces an emission spectrum having a peak at a wavelength of equal to or greater than 590 nm but equal to or less than 630 nm and having a full width at half maximum of 130 nm or greater at the peak, the full width at half maximum of the emission spectrum of the orange phosphor (13) being broader than a full width at half maximum of an emission spectrum of the green phosphor (14). The orange phosphor (13) exhibits an absorptance having a peak wavelength of 420 nm or greater. ABS(530) and ABS(MAX) satisfy a relation, ABS(530)/ABS(MAX) < 0.60, where ABS(MAX) is an absorptance of the orange phosphor (13) at the peak wavelength thereof, and ABS(530) is an absorptance of the orange phosphor (13) at a wavelength of 530 nm.


Ariga K.,Japan National Institute of Materials Science | Ariga K.,Japan Science and Technology Agency | Ji Q.,Japan National Institute of Materials Science | Mori T.,Japan National Institute of Materials Science | And 10 more authors.
Chemical Society Reviews | Year: 2013

Fabrication of ultrasmall functional machines and their integration within ultrasmall areas or volumes can be useful for creation of novel technologies. The ultimate goal of the development of ultrasmall machines and device systems is to construct functional structures where independent molecules operate as independent device components. To realize exotic functions, use of enzymes in device structures is an attractive solution because enzymes can be regarded as efficient machines possessing high reaction efficiencies and specificities and can operate even under ambient conditions. In this review, recent developments in enzyme immobilization for advanced functions including device applications are summarized from the viewpoint of micro/nano-level structural control, or nanoarchitectonics. Examples are roughly classified as organic soft matter, inorganic soft materials or integrated/organized media. Soft matter such as polymers and their hybrids provide a medium appropriate for entrapment and encapsulation of enzymes. In addition, self-immobilization based on self-assembly and array formation results in enzyme nanoarchitectures with soft functions. For the confinement of enzymes in nanospaces, hard inorganic mesoporous materials containing well-defined channels play an important role. Enzymes that are confined exhibit improved stability and controllable arrangement, which are useful for formation of functional relays and for their integration into artificial devices. Layer-by-layer assemblies as well as organized lipid assemblies such as Langmuir-Blodgett films are some of the best media for architecting controllable enzyme arrangements. The ultrathin forms of these films facilitate their connection with external devices such as electrodes and transistors. Artificial enzymes and enzyme-mimicking catalysts are finally briefly described as examples of enzyme functions involving non-biological materials. These systems may compensate for the drawbacks of natural enzymes, such as their instabilities under harsh conditions. We believe that enzymes and their mimics will be freely coupled, organized and integrated upon demand in near future technologies. © 2013 The Royal Society of Chemistry.


Gorbachev R.V.,University of Manchester | Geim A.K.,University of Manchester | Katsnelson M.I.,Radboud University Nijmegen | Novoselov K.S.,University of Manchester | And 8 more authors.
Nature Physics | Year: 2012

Coulomb drag is a frictional coupling between electric currents flowing in spatially separated conducting layers. It is caused by interlayer electron-electron interactions. Previously, only the regime of weak (d ≫ l) to intermediate (d∼l) coupling could be studied experimentally, where d is the interlayer separation and l is the characteristic distance between charge carriers. Here we use graphene-boron-nitride heterostructures with d down to 1nm to probe Coulomb drag in the limit d ≪ l such that the two Dirac liquids effectively nest within the same plane, but can still be tuned and measured independently. The strongly interacting regime reveals many unexpected features. In particular, although drag vanishes because of electron-hole symmetry when either layer is neutral, we often find drag strongest when both layers are neutral. Under this circumstance, drag is positive in zero magnetic field but changes its sign and rapidly grows in strength with field. The drag remains strong at room temperature. The broken electron-hole symmetry is attributed to mutual polarization of closely spaced interacting layers. © 2012 Macmillan Publishers Limited. All rights reserved.


Kimoto K.,Japan National Institute of Materials Science | Ishizuka K.,INC Research
Ultramicroscopy | Year: 2011

We demonstrate spatially resolved diffractometry in which diffraction patterns are acquired at two-dimensional positions on a specimen using scanning transmission electron microscopy (STEM), resulting in four-dimensional data acquisition. A high spatial resolution of about 0.1. nm is achieved using a stabilized STEM instrument, a spherical aberration corrector and various post-acquisition data processings. We have found a few novel results in the radial and the azimuthal scattering angle dependences of atomic-column contrast in STEM images. Atomic columns are clearly observed in dark field images obtained using the excess Kikuchi band intensity even in small solid-angle detection. We also find that atomic-column contrasts in dark field images are shifted in the order of a few tens of picometers on changing the azimuthal scattering angle. This experimental result is approximately interpretable on the basis of the impact parameter in Rutherford scattering. Spatially resolved diffractometry provides fundamental knowledge related to various STEM techniques, such as annular dark field (ADF) and annular bright field (ABF) imaging, and it is expected to become an analytical platform for advanced STEM imaging. © 2011 Elsevier B.V.


Ariga K.,Japan Science and Technology Agency | Ariga K.,Japan National Institute of Materials Science | Ito H.,Japan Science and Technology Agency | Ito H.,Osaka City University | And 4 more authors.
Chemical Society Reviews | Year: 2012

In the 25 years since its Nobel Prize in chemistry, supramolecular chemistry based on molecular recognition has been paid much attention in scientific and technological fields. Nanotechnology and the related areas seek breakthrough methods of nanofabrication based on rational organization through assembly of constituent molecules. Advanced biochemistry, medical applications, and environmental and energy technologies also depend on the importance of specific interactions between molecules. In those current fields, molecular recognition is now being re-evaluated. In this review, we re-examine current trends in molecular recognition from the viewpoint of the surrounding media, that is (i) the solution phase for development of basic science and molecular design advances; (ii) at nano/materials interfaces for emerging technologies and applications. The first section of this review includes molecular recognition frontiers, receptor design based on combinatorial approaches, organic capsule receptors, metallo-capsule receptors, helical receptors, dendrimer receptors, and the future design of receptor architectures. The following section summarizes topics related to molecular recognition at interfaces including fundamentals of molecular recognition, sensing and detection, structure formation, molecular machines, molecular recognition involving polymers and related materials, and molecular recognition processes in nanostructured materials. © The Royal Society of Chemistry 2012.


Hosokawa A.,McMaster University | Hosokawa A.,Japan National Institute of Materials Science | Wilkinson D.S.,McMaster University | Kang J.,CanmetMATERIALS | Maire E.,INSA Lyon
Acta Materialia | Year: 2013

Void growth and coalescence in model materials containing a pre-existing three-dimensional void array were studied by X-ray computed tomography coupled with in situ uniaxial tensile deformation. A newly developed continuous tomography technique was employed to capture the onset of coalescence. Using a picosecond laser machining system and a diffusion bonding technique, model materials with different void geometries were prepared. By implementing continuous tomography, the plastic strain at the onset of void coalescence was measured (instead of simple linkage) for the first time. The plastic strains at the onset of void coalescence were compared with the existing void coalescence models. Finite-element (FE) simulations were performed to study the influences of void shape (sphere, cylinder, tapered-cylinder) on the void growth behavior. This study shows that the coalescence models developed by Thomason and later extended by Pardoen and Hutchinson provide accurate predictions of coalescence strain when the voids are aligned normal to the tensile axis. However, offsets can induce shear effects that lower the coalescence strain in a manner not predicted by the models. Two-dimensional plane-strain FE simulations were also used to explore the influence of shear localization between two misaligned coalescing voids on ductility. These demonstrate the nature of the effect. © 2012 and Elsevier Ltd. Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Withers F.,University of Manchester | Del Pozo-Zamudio O.,University of Sheffield | Mishchenko A.,University of Manchester | Rooney A.P.,University of Manchester | And 7 more authors.
Nature Materials | Year: 2015

The advent of graphene and related 2D materials has recently led to a new technology: heterostructures based on these atomically thin crystals. The paradigm proved itself extremely versatile and led to rapid demonstration of tunnelling diodes with negative differential resistance, tunnelling transistors, photovoltaic devices and so on. Here, we take the complexity and functionality of such van der Waals heterostructures to the next level by introducing quantum wells (QWs) engineered with one atomic plane precision. We describe light-emitting diodes (LEDs) made by stacking metallic graphene, insulating hexagonal boron nitride and various semiconducting monolayers into complex but carefully designed sequences. Our first devices already exhibit an extrinsic quantum efficiency of nearly 10% and the emission can be tuned over a wide range of frequencies by appropriately choosing and combining 2D semiconductors (monolayers of transition metal dichalcogenides). By preparing the heterostructures on elastic and transparent substrates, we show that they can also provide the basis for flexible and semi-transparent electronics. The range of functionalities for the demonstrated heterostructures is expected to grow further on increasing the number of available 2D crystals and improving their electronic quality. © 2015 Macmillan Publishers Limited. All rights reserved.


Choi M.S.,Sungkyunkwan University | Qu D.,Sungkyunkwan University | Lee D.,Sungkyunkwan University | Liu X.,Sungkyunkwan University | And 3 more authors.
ACS Nano | Year: 2014

This paper demonstrates a technique to form a lateral homogeneous 2D MoS2 p-n junction by partially stacking 2D h-BN as a mask to p-dope MoS2. The fabricated lateral MoS2 p-n junction with asymmetric electrodes of Pd and Cr/Au displayed a highly efficient photoresponse (maximum external quantum efficiency of ∼7000%, specific detectivity of ∼5 × 1010 Jones, and light switching ratio of ∼103) and ideal rectifying behavior. The enhanced photoresponse and generation of open-circuit voltage (VOC) and short-circuit current (ISC) were understood to originate from the formation of a p-n junction after chemical doping. Due to the high photoresponse at low VD and VG attributed to its built-in potential, our MoS2 p-n diode made progress toward the realization of low-power operating photodevices. Thus, this study suggests an effective way to form a lateral p-n junction by the h-BN hard masking technique and to improve the photoresponse of MoS2 by the chemical doping process. © 2014 American Chemical Society.


Horvath B.,Japan National Institute of Materials Science | Horvath B.,Budapest University of Technology and Economics
Microelectronics Reliability | Year: 2013

Whisker growth on electroplated bright (grain size < 0.5 μm) tin layers is examined and discussed in terms of the variety of shapes formed. Whiskers may be categorized by three basic morphological types of crystal structure which are usually observed on tin-based finishes (hillocks, nodules and filaments). In this paper, analysis of different whisker shapes and the reason for their development are defined. Constant elevated temperature in ambient humidity (105 °C/15% relative humidity) tests were used to accelerate the growth of very large whiskers (>50 μm nodule/hillock base) through enhanced diffusion, and to minimize the effect of corrosion on the samples. Cross sections from the layers and whiskers were etched and observed using a Focused Ion Beam (FIB). Transmission Electron Microscopy (TEM) was used to analyze the developing whiskers and to provide insight on the development of hillocks, nodules and filaments. Results indicate that fragmentation of a hillock/nodule, and later mass migration and segregation of copper, are critical steps in the evolution of these large whiskers. Copper impurities segregating at the whisker grain boundaries are responsible for the development of various whisker shapes. © 2013 Elsevier Ltd. All rights reserved.


Patent
Japan National Institute of Materials Science and French National Center for Scientific Research | Date: 2010-11-03

A method of manufacturing a diamond UV sensor element improved with a UV/visible light blind ratio using a diamond single crystal as a light receiving portion and detecting a light based on the change of electric resistance caused by a light irradiated to the light receiving portion is provided, the method, including (1) a step of hydrogenating the surface of the diamond single crystal in an atmosphere substantially containing hydrogen, and (2) a step of forming a light receiving portion by exposing the hydrogenated surface of the diamond single crystal into an atmosphere containing ozone or active oxygen.


Grant
Agency: GTR | Branch: EPSRC | Program: | Phase: Research Grant | Award Amount: 43.23K | Year: 2012

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.


Iliev H.,Sofia University | Buchvarov I.,Sofia University | Kurimura S.,Japan National Institute of Materials Science | Petrov V.,Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy
Optics Letters | Year: 2010

Periodically poled stoichiometric lithium-tantalate is used for mode locking of a diode-pumped Nd: GdVO4 laser by intracavity second-harmonic generation. Stable and self-starting operation is observed achieving average output powers of up to 5 W at a pulse-repetition rate of 107 MHz. The obtained pulse durations range from 6.5 ps at maximum output power down to 3.2 ps at 1.4 W. © 2010 Optical Society of America.


Chandni U.,California Institute of Technology | Watanabe K.,Japan National Institute of Materials Science | Taniguchi T.,Japan National Institute of Materials Science | Eisenstein J.P.,California Institute of Technology
Nano Letters | Year: 2015

We investigate electron tunneling through atomically thin layers of hexagonal boron nitride (hBN). Metal (Cr/Au) and semimetal (graphite) counter-electrodes are employed. While the direct tunneling resistance increases nearly exponentially with barrier thickness as expected, the thicker junctions also exhibit clear signatures of Coulomb blockade, including strong suppression of the tunnel current around zero bias and step-like features in the current at larger biases. The voltage separation of these steps suggests that single-electron charging of nanometer-scale defects in the hBN barrier layer are responsible for these signatures. We find that annealing the metal-hBN-metal junctions removes these defects and the Coulomb blockade signatures in the tunneling current. © 2015 American Chemical Society.


Hollamby M.J.,Keele University | Nakanishi T.,Japan National Institute of Materials Science
Journal of Materials Chemistry C | Year: 2013

The power of branched alkyl substituents to alter material properties is known to soft matter chemistry, with examples found in both surfactants and ionic liquids. Here, we highlight their potency in organic molecular/polymeric materials with optoelectronic applications. Attaching branched alkyl chains to the active π-conjugated core modulates core-core interactions and thus softens the material. This can lead to optimised assemblies with improved optoelectronic properties. By increasing the number and volume of the flexible chains, individual cores can be isolated, yielding functional organic liquids with bulk optical properties the same as the intrinsic molecular characteristics obtained for their dilute solutions. These liquid materials can accommodate dopants to offer diverse and tuneable emission colours, and provide an easily applicable flexible and foldable continuous layer for future optoelectronic media. © 2013 The Royal Society of Chemistry.


Hiraga T.,University of Tokyo | Miyazaki T.,University of Tokyo | Yoshida H.,Japan National Institute of Materials Science | Zimmerman M.E.,University of Minnesota
Geology | Year: 2013

We conducted compressional, tensile, and torsional creep experiments on fine-grained forsterite plus Ca-bearing pyroxene aggregates. A distinct microstructure with aggregation of the same phase in the direction of compression was formed in our samples after all the experiments. The stress-strain rate relationship, grain-size dependent flow strength, and the achievement of large tensile strain all indicate that samples underwent creep due to grain boundary sliding (GBS). As a result of GBS, grain-switching events allow dispersed phases to contact grains of the same phase and orient in the direction of compression. We identify similar aggregated microstructures in previously reported micrographs of polymineralic graniteorigin ultramylonites. Mineral phase mixing through GBS, which helps to retain fine grain size in rocks due to grain boundary pinning, has been speculated to occur during formation of mylonites. However, our results contradict this hypothesis because mineral aggregation through GBS promotes demixing rather than mixing of the mineral phases. GBS processes alone will not promote a transformation of well-developed monomineralic bands to polymineralic bands during mylonitization. © 2013 Geological Society of America.


Hiraga T.,University of Tokyo | Tachibana C.,University of Tokyo | Ohashi N.,Japan National Institute of Materials Science | Sano S.,Ube Industries
Earth and Planetary Science Letters | Year: 2010

Grain growth kinetics of forsterite (Fo) and enstatite (En) in fine grain aggregates of Fo ± En are examined as a function of volume fraction of En (fEn = 0.00 to 0.42). Growth rates fit dn∝ k · t (d: mean grain diameter; n: grain growth exponent; k: growth constant; t: time), where n ∼ 5 for both forsterite and enstatite grains in the enstatite-bearing samples. A negative correlation between kFo and fEn can be expressed as kFo ≈ 0.06 exp [30 fEn (fEn - 1.1)], whereas kEn takes almost constant values for different fEn. In addition, the ratio of dFo/dEn is almost constant during grain growth, and its value becomes smaller with increasing fEn, such that dFo/dEn ≈ 0.74/fEn0.59. Our obtained grain growth parameters and the microstructural characteristics in experimental and natural samples all indicate that the rate-controlling process for grain growth in both experiments and in nature is grain boundary diffusion of Si through grain boundaries of olivine. Thus, we are able to propose a semi-empirical relationship of dAve / ddun ≈ {exp [30 fpx {dot operator} (fpx - 1.1)]}frac(1, 5) {dot operator} (1 + 1.35 fpx 1.59 - fpx) (dAve: average grain size in the rock; ddun: average grain size in dunite; fpx: fraction of pyroxenes), which can predict how lithology affects grain size in the upper mantle. Grain size in lherzolite (pyroxenes content of 40%) can be ∼ 4 times smaller than that in dunite (pyroxenes content of 5%). Such grain size reduction through change in lithology can significantly affect viscosity of mantle deformation via grain-size sensitive creep. © 2009 Elsevier B.V. All rights reserved.


Kang Y.,Japan National Institute of Materials Science | Kang S.,Seoul National University
Journal of the European Ceramic Society | Year: 2010

A ceramic microstructure of WC-reinforced (Ti,W)(CN) was designed using thermodynamic instability among the constituent elements and gas species involved in the sintering process. During sintering WC in the shape of platelets formed in (Ti,W)(CN) solid-solution ceramics, which were synthesized from milled mixtures of oxides with carbon. The WC platelets separated from the (Ti,W)(CN) ceramics due to the low chemical affinity of tungsten for nitrogen. The shape of WC varies depending on the composition of the binder phase and the sintering conditions. With increasing binder content, the WC platelet shape became more irregular. This change was attributed not only to surface energy but also to the formation mechanism. The presence of WC platelets toughened (Ti,W)(CN) significantly at excellent hardness value (Hv: 18.5-20.0 GPa, KIC: 6.0-6.8 MPa m1/2) as compared to those of recently reported advanced structural ceramics. © 2009 Elsevier Ltd. All rights reserved.


Lodge T.P.,University of Minnesota | Ueki T.,Japan National Institute of Materials Science
Accounts of Chemical Research | Year: 2016

ConspectusRoom temperature ionic liquids are of great interest for many advanced applications, due to the combination of attractive physical properties with essentially unlimited tunability of chemical structure. High chemical and thermal stability, favorable ionic conductivity, and complete nonvolatility are just some of the most important physical characteristics that make ionic liquids promising candidates for emerging technologies. Examples include separation membranes, actuators, polymer gel electrolytes, supercapacitors, ion batteries, fuel cell membranes, sensors, printable plastic electronics, and flexible displays. However, in these and other applications, it is essential to solidify the ionic liquid, while retaining the liquid state properties of interest.A broadly applicable solidification strategy relies on gelation by addition of suitable triblock copolymers with the ABA architecture, producing ion gels or ionogels. In this paradigm, the A end blocks are immiscible with the ionic liquid, and consequently self-assemble into micellar cores, while some fraction of the well-solvated B midblocks bridge between micelles, forming a percolating network. The chemical structures of the A and B repeat units, the molar mass of the blocks, and the concentration of the copolymer in the ionic liquid are all independently tunable to attain desired property combinations. In particular, the modulus of the resulting ion gel can be readily varied between 100 Pa and 1 MPa, with little sacrifice of the transport properties of the ionic liquid, such as ionic conductivity or gas diffusivity. Suitable A blocks can impart thermoreversible gelation (with solidification either on heating or cooling) or even photoreversible gelation.By virtue of the nonvolatility of ionic liquids, a wide range of processing strategies can be employed directly to prepare ion gels in thin or thick film forms, including solvent casting, spin coating, aerosol jet printing, photopatterning, and transfer printing. For higher modulus ion gels it is even possible to employ a manual "cut and stick" strategy for easy device fabrication. Ion gels prepared from common triblock copolymers, for example, with A = polystyrene and B = poly(ethylene oxide) or poly(methyl methacrylate), in imidazolium based ionic liquids provide exceptional performance in membranes for separating CO2 from N2 or CH4. The same materials also are the best available gate dielectrics for printed plastic electronics, because their high capacitance endows organic transistors with milliamp output currents for sub-1 V applied bias, with switching speeds that can go well beyond 100 kHz, while being amenable to large area roll-to-roll printing. Incorporation of well-designed electroluminescent (e.g., Ru(bpy)3-based) or electrochromic (e.g., viologen-based) moieties into ion gels held between transparent electrodes yields flexible color displays operating with sub-1 V dc inputs. © 2016 American Chemical Society.


Nikiforov I.,University of Minnesota | Tang D.-M.,Japan National Institute of Materials Science | Wei X.,Japan National Institute of Materials Science | Dumitrica T.,University of Minnesota | Golberg D.,Japan National Institute of Materials Science
Physical Review Letters | Year: 2012

By combining experiments performed on nanoribbons in situ within a high-resolution TEM with objective molecular dynamics simulations, we reveal common mechanisms in the bending response of few-layer-thick hexagonal boron nitride and graphene nanoribbons. Both materials are observed forming localized kinks in the fully reversible bending experiments. Microscopic simulations and theoretical analysis indicate platelike bending behavior prior to kinking, in spite of the possibility of interlayer sliding, and give the critical curvature for the kinking onset. This behavior is distinct from the rippling and kinking of multi- and single-wall nanotubes under bending. Our findings have implications for future study of nanoscale layered materials, including nanomechanical device design. © 2012 American Physical Society.


Gao J.-H.,Japan National Institute of Materials Science | Ishida N.,Japan National Institute of Materials Science | Scott I.,University of Minnesota | Fujita D.,Japan National Institute of Materials Science
Carbon | Year: 2012

Using a surface segregation technique, single-layer graphene can be grown on a carbon-doped Pd(1 1 1) substrate. The growth was monitored and visualized using Auger electron spectroscopy, X-ray photoelectron spectroscopy, Raman microscopy, atomic force microscopy and scanning tunneling microscopy. Appropriate adjustment of annealing parameters enables controllable growth of single-layer graphene islands and homogeneous, wafer-scale, single-layer graphene. The chemical state of the C 1s peak from X-ray photoelectron spectroscopy indicates there is almost no charge transfer between graphene and the Pd(1 1 1) substrate, suggesting weak graphene-substrate interaction. These findings show surface segregation to be an effective method for synthesizing large-scale graphene for fundamental research as well as potential applications. © 2011 Elsevier Ltd. All rights reserved.


Dean C.R.,Columbia University | Young A.F.,Columbia University | Meric I.,Columbia University | Lee C.,University of Suwon | And 7 more authors.
Nature Nanotechnology | Year: 2010

Graphene devices on standard SiO 2 substrates are highly disordered, exhibiting characteristics that are far inferior to the expected intrinsic properties of graphene. Although suspending the graphene above the substrate leads to a substantial improvement in device quality, this geometry imposes severe limitations on device architecture and functionality. There is a growing need, therefore, to identify dielectrics that allow a substrate-supported geometry while retaining the quality achieved with a suspended sample. Hexagonal boron nitride (h-BN) is an appealing substrate, because it has an atomically smooth surface that is relatively free of dangling bonds and charge traps. It also has a lattice constant similar to that of graphite, and has large optical phonon modes and a large electrical bandgap. Here we report the fabrication and characterization of high-quality exfoliated mono-and bilayer graphene devices on single-crystal h-BN substrates, by using a mechanical transfer process. Graphene devices on h-BN substrates have mobilities and carrier inhomogeneities that are almost an order of magnitude better than devices on SiO2. These devices also show reduced roughness, intrinsic doping and chemical reactivity. The ability to assemble crystalline layered materials in a controlled way permits the fabrication of graphene devices on other promising dielectrics and allows for the realization of more complex graphene heterostructures. © 2010 Macmillan Publishers Limited. All rights reserved.


Patent
Koha Co., Tamura Corporation and Japan National Institute of Materials Science | Date: 2016-06-15

Provided is a light emitting device which is suitable for a lighting apparatus, such as a projector, requiring high brightness and high light intensity exhibits little change in light emission colour and a low reduction in light emission intensity during usage, and uses a remote phosphor. According to one embodiment of the present invention, the light emitting device (10) has: an LED element (12); a side wall (13) which surrounds the LED element (12); a phosphor layer (15) which is fixed to the side wall (13) with an adhesive layer (14) therebetween, and is positioned above the LED element (12); and a metal pad (11) as a heat dissipating member. The side wall (13) has: an insulating base (13b) which surrounds the LED element (12); and a metal layer (13a) which is formed on a side surface at the LED element (12) side of the base (13b), and is in contact with the metal pad (11) and the adhesive layer (14). The adhesive layer (14) is: a resin layer that comprises a resin containing particles which have higher thermal conductivity than the resin; or a layer that comprises solder.


Patent
Koha Co. and Japan National Institute of Materials Science | Date: 2013-04-18

A phosphor (and a method for manufacturing the same, and a light-emitting device that uses this phosphor) includes single crystals including YAG crystals as a mother crystal, the quantum efficiency of the phosphor at 25 C. being 92% or higher at an excitation light wavelength of 460 nm.


Patent
Japan National Institute of Materials Science and Honda Corporation | Date: 2011-11-09

There is provided a nickel alloy having an excellent creep strength as well as high-temperature oxidation resistance. The nickel alloy of the present invention comprises, by mass percent, Cr in a range of 11.5 to 11.9%, Co in a range of 25 to 29%, Mo in a range of 3.4 to 3.7%, W in a range of 1.9 to 2.1%, Ti in a range of 3.9 to 4.4%, Al in a range of 2.9 to 3.2%, C in a range of 0.02 to 0.03%, B in a range of 0.01 to 0.03%, Zr in a range of 0.04 to 0.06%, Ta in a range of 2.1 to 2.2%, Hf in a range of 0.3 to 0.4%, and Nb in a range of 0.5 to 0.8%, the balance being Ni and unavoidable impurities, and contains carbides and borides precipitating in crystal grains and at grain boundaries.


Patent
Koha Co. and Japan National Institute of Materials Science | Date: 2016-03-30

Provided are: a YAG-based single crystal phosphor which produces fluorescence of a non-conventional color; and a phosphor-containing member and a light emitting device, each of which is provided with this single crystal phosphor. Provided as one embodiment of the present invention is a single crystal phosphor which has a composition represented by composition formula (Y_(1-a-b)Lu_(a)Ce_(b))_(3+c)Al_(5-c)O_(12) (wherein 0 a 0.9994, 0.0002 b 0.0067 and -0.016 c 0.315), and which has an emission spectrum having CIE chromaticity coordinates x and y satisfying the relation -0.4377x + 0.7384 y -0.4585x + 0.7504 when the peak wavelength of the excitation light is 450 nm at the temperature of 25C.


Provided is a structure having a perpendicular magnetization film which is an (Mn_(1-x),Ga_(x))_(4)N_(1-y )(0


Patent
Koha Co. and Japan National Institute of Materials Science | Date: 2015-03-04

One purpose of the invention is to provide a phosphor with excellent quantum efficiency, a method for manufacturing the same, and a light-emitting device that uses this phosphor. One embodiment provides a phosphor comprising monocrystals with YAG crystals as a matrix, the quantum efficiency of the phosphor at 25C being 92% or higher at an excitation light wavelength of 460 nm.


Patent
Honda Corporation and Japan National Institute of Materials Science | Date: 2013-06-12

There is provided a nickel alloy having an excellent creep strength as well as high-temperature oxidation resistance. The nickel alloy of the present invention comprises, by mass percent, Cr in a range of 11.5 to 11.9%, Co in a range of 25 to 29%, Mo in a range of 3.4 to 3.7%, W in a range of 1.9 to 2.1%, Ti in a range of 3.9 to 4.4%, Al in a range of 2.9 to 3.2%, C in a range of 0.02 to 0.03%, B in a range of 0.01 to 0.03%, Zr in a range of 0.04 to 0.06%, Ta in a range of 2.1 to 2.2%, Hf in a range of 0.3 to 0.4%, and Nb in a range of 0.5 to 0.8%, the balance being Ni and unavoidable impurities, and contains carbides and borides precipitating in crystal grains and at grain boundaries.


Patent
Koha Co. and Japan National Institute of Materials Science | Date: 2016-08-31

As one of purposes, the present invention provides: a single-crystal phosphor which can exhibit excellent properties under high-temperature conditions; and a light-emitting device in which the phosphor is used. As one embodiment, a single-crystal phosphor is provided, which has a chemical composition represented by the compositional formula: (Y_(1-x-y-z)Lu_(x)Gd_(y)Ce_(z))_(3+a)Al_(5-a)O_(12) (0 x 0.9994, 0 y 0.0669, 0.0002 z 0.0067, -0.016 a 0.315).


Patent
Japan National Institute of Materials Science and KOHA Co. | Date: 2011-10-28

[Problem] To provide a light-emitting device which does not undergo the deterioration in luminous efficiency associated with the long-term use. [Solution] A light-emitting device (1) comprises a light-emitting element (10) which can emit blue light and a phosphor (2) which is composed of a single kind of single crystal and can emit yellow light upon the irradiation with the light emitted from the light-emitting element (10) which serves as excitation light. Thus, it becomes possible to prevent the deterioration in luminous efficiency associated with the deterioration in a binder or the like compared with a light-emitting device which utilizes multiple kinds of granular phosphors, because any binder for binding phosphors to each other is not required in the light-emitting device (1).


Patent
Koha Co. and Japan National Institute of Materials Science | Date: 2014-10-20

As one of purposes, the present invention provides: a single-crystal phosphor which can exhibit excellent properties under high-temperature conditions; and a light-emitting device in which the phosphor is used. As one embodiment, a single-crystal phosphor is provided, which has a chemical composition represented by the compositional formula: (Y_(1-x-y-z)Lu_(x)Gd_(y)Ce_(z))_(3+a)Al_(5-a)O_(12)(0x0.9994, 0y0.0669, 0.0002z0.0067, 0.016a0.315).


Patent
Koha Co., Tamura Corporation and Japan National Institute of Materials Science | Date: 2014-08-08

According to one embodiment of the present invention, the light emitting device includes an LED element, a side wall which surrounds the LED element, a phosphor layer which is fixed to the side wall with an adhesive layer therebetween, and is positioned above the LED element, and a metal pad as a heat dissipating member. The side wall includes an insulating base which surrounds the LED element and a metal layer which is formed on a side surface at the LED element side of the base, and is in contact with the metal pad and the adhesive layer. The adhesive layer includes a resin layer that includes a resin containing particles which have higher thermal conductivity than the resin or a layer that includes solder.

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