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Xie G.,Advanced Institute for Materials Research | Li S.,Advanced Institute for Materials Research | Louzguine-Luzgin D.V.,Advanced Institute for Materials Research | Sato M.,Japan National Institute for Fusion Science | Inoue A.,Tohoku University
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2010

Using a gas-atomized Ni59.35Nb34.45Sn6.2 metallic glassy alloy powder blended with Sn powder of various contents, Ni-Nb-Sn bulk metallic glassy matrix composites were fabricated by a microwave (MW)-induced sintering process in a single-mode 2.45 GHz MW applicator in a separated magnetic field. The Ni59.35Nb34.45Sn 6.2 glassy alloy powder and its mixed powders containing Sn particles could be heated well in the magnetic field. The addition of Sn particles promoted densification of the sintered Ni59.35Nb 34.45Sn6.2 metallic glassy powder. Bulk samples without crystallization of the glassy matrix and with good bonding state among the particles were achieved at a sintering temperature of 833 K. © The Minerals, Metals & Materials Society and ASM International 2009.

Abstract: An international research team at Tohoku University's Advanced Institute of Materials Research (AIMR) succeeded in chemically interconnecting chiral-edge graphene nanoribbons (GNRs) with zigzag-edge features by molecular assembly, and demonstrated electronic connection between GNRs. The GNRs were interconnected exclusively end to end, forming elbow structures, identified as interconnection points (Fig. 1a). This configuration enabled researchers to demonstrate that the electronic architecture at the interconnection points between two GNRs (Fig. 1b) is the same as that along single GNRs; evidence that GNR electronic properties, such as electron and thermal conductivities, are directly extended through the elbow structures upon chemical GNR interconnection. This work shows that future development of high-performance, low-power-consumption electronics based on GNRs is possible. Graphene has long been expected to revolutionize electronics, provided that it can be cut into atomically precise shapes that are connected to desired electrodes. However, while current bottom-up fabrication methods can control graphene's electronic properties, such as high electron mobility, tailored band gaps and s pin-aligned zigzag edges, the connection aspect of graphene structures has never been directly explored. For example, whether electrons traveling across the interconnection points of two GNRs would encounter higher electric resistance remains an open question. As the answers to this type of questions are crucial towards the realization of future high-speed, low-power-consumption electronics, we use molecular assembly to address this issue here. "Current molecular assemblies either produce straight GNRs (i.e., without identifiable interconnection points), or randomly interconnected GNRs," says Dr. Patrick Han, the project leader. "These growth modes have too many intrinsic unknowns for determining whether electrons travel across graphene interconnection points smoothly. The key is to design a molecular assembly that produces GNRs that are systematically interconnected with clearly distinguishable interconnection points." To reach this goal, the AIMR team used a Cu substrate, whose reactivity confines the GNR growth to six directions, and used scanning tunneling microscopy (STM) to visualize the GNR electronic structures. By controlling the precursor molecular coverage, this molecular assembly connects GNRs from different growth directions systematically end to end, producing elbow structures--identified as interconnection points (Fig. 1a). Using STM, the AIMR team revealed that the delocalization of the interconnected GNR π*-states extends the same way both across a single straight GNR, and across the interconnection point of two GNRs (periodic features in Fig. 1b, bottom panel). This result indicates that GNR electronic properties, such as electron and thermal conductivities, should be the same at the termini of single GNRs and that of two connected GNRs. "The major finding of this work is that interconnected GNRs do not show electronic disruption (e.g., electron localization that increases resistance at the interconnection points)," says Han. "The electronically smooth interconnection demonstrates that GNR properties (including tailored band gaps, or even spin-aligned zigzag edges) can be connected to other graphene structures. These results show that finding a way to connect defect-free GNRs to desired electrodes may be the key strategy toward achieving high-performance, low-power-consumption electronics." About Tohoku University The Advanced Institute for Materials Research (AIMR) at Tohoku University is one of nine World Premier International Research Center Initiative (WPI) Programs established with the support of the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT). The program aims to develop world-class research bases in Japan. After its establishment in 2007, AIMR has been active in conducting research activities and creating new systems in order to become a global center for materials science. Since 2012, AIMR has also been conducting fundamental research by finding connections between materials science and mathematics. Learn more at www.wpi-aimr.tohoku.ac.jp For more information, please click Contacts: Patrick Han 81-222-176-170 For information on AIMR and all other enquiries: Marie Minagawa Public Relations & Outreach office Advanced Institute for Materials Research, Tohoku University aimr-outreachgrp.tohoku.ac.jp Fax: +81-22-217-6146 If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Umezawa K.,Tohoku University | Li Y.,Renmin University of China | Miao H.,CAS Institute of Physics | Nakayama K.,Tohoku University | And 11 more authors.
Physical Review Letters | Year: 2012

We have performed high-resolution angle-resolved photoemission spectroscopy on Fe-based superconductor LiFeAs (T c=18K). We reveal multiple nodeless superconducting (SC) gaps with 2Δ/k BT c ratios varying from 2.8 to 6.4, depending on the Fermi surface (FS). We also succeeded in directly observing a gap anisotropy along the FS with magnitude up to ∼30%. The anisotropy is fourfold symmetric with an antiphase between the hole and electron FSs, suggesting complex anisotropic interactions for the SC pairing. The observed momentum dependence of the SC gap offers an excellent opportunity to investigate the underlying pairing mechanism. © 2012 American Physical Society.

Wakimoto S.,Japan Atomic Energy Agency | Hiraka H.,Tohoku University | Kudo K.,Tohoku University | Kudo K.,Okayama University | And 10 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We report electrical-resistivity measurements and neutron-diffraction studies under magnetic fields of Bi1.75 Pb0.35 Sr 1.90 Cu0.91 Fe0.09 O6+y, in which hole carriers are overdoped. This compound shows short-range incommensurate magnetic correlation with incommensurability δ=0.21, whereas a Fe-free compound shows no magnetic correlation. Resistivity shows an up turn at low temperature in the form of ln (1/T) and shows no superconductivity. We observe reduction in resistivity by applying magnetic fields (i.e., a negative magnetoresistive effect) at temperatures below the onset of short-range magnetic correlation. Application of magnetic fields also suppresses the Fe-induced incommensurate magnetic correlation. We compare and contrast these observations with two different models: (1) stripe order and (2) dilute magnetic moments in a metallic alloy with associated Kondo behavior. The latter picture appears to be more relevant to the present results. © 2010 The American Physical Society.

Lu J.,Advanced Institute for Materials Research | Minami K.,Advanced Institute for Materials Research | Takami S.,Tohoku University | Shibata M.,Idemitsu Kosan Co. | And 3 more authors.
ACS Applied Materials and Interfaces | Year: 2012

ITO nanoparticles were synthesized hydrothermally and surface modified in supercritical water using a continuous flow reaction system. The organic modification of the nanoparticles converted the surface from hydrophilic to hydrophobic, making the modified nanoparticles easily dispersible in organic solvent. The addition of a surface modifier into the reaction system impacted the crystal growth and particle size as well as dispersion. The particle size was 18 nm. Highly crystalline cubic ITO with a narrow particle size distribution was obtained. The advantages of short reaction time and the use of a continuous reaction system make this method suitable for industrial scale synthesis. © 2011 American Chemical Society.

Kasuya M.,Tohoku University | Mizukami M.,Tohoku University | Kurihara K.,Tohoku University | Kurihara K.,Advanced Institute for Materials Research
Bunseki Kagaku | Year: 2010

Surface force measurements represent a powerful tool for the molecular-level characterization of water at solid-liquid interfaces, which is important for various functionalized interfaces, including biointerfaces. We have studied the properties of interfacial water using surface force measurements and resonance shear measurements, which we developed. This paper summarizes some of our recent research : (1) water confined between mica surfaces and (2) the molecular macrocluster formation of water adsorbed on silica surfaces. © 2010 The Japan Society for Analytical Chemistry.

Yanagida H.,Tohoku University | Yoshida S.,Tohoku University | Yoshida S.,Advanced Institute for Materials Research | Esashi M.,Tohoku University | And 2 more authors.
IEEJ Transactions on Sensors and Micromachines | Year: 2011

We have developed the etching technology using an ozone solution for chemically stable polymers such as polyimide, SU-8 and BCB, which are often used for MEMS, and a carbonized resist. Conventionally, these polymers are difficult to remove by O2 plasma and organic solutions. In this study, the etching experiments of these chemically stable polymers were carried out using an acetic solution of ozone. The residues after the etching of the polymers were evaluated with surface profiler, scanning electron microscope and X-ray photoelectron spectroscopy. It was demonstrated that the acetic solution of ozone can etch and remove these polymers without residue. The developed method can remove not only organic polymers but also polymers containing inorganic materials, and is safe and easy. © 2011 The Institute of Electrical Engineers of Japan.

Takahashi T.,Tohoku University | Makihata M.,Tohoku University | Esashi M.,Advanced Institute for Materials Research | Tanaka S.,Tohoku University
IEEJ Transactions on Sensors and Micromachines | Year: 2010

ProTEK PSB and ProTEK B3 (Brewer Science, Inc.) are negative type photosensitive resist and non-photosensitive resist for alkaline wet etching, respectively. This paper mainly reports the patterning characteristics, etch resistance and removal characteristics of ProTEK PSB under practical conditions for a real application. Our study found two problems of ProTEK PSB: unacceptably-large side-etching and difficulty in removing the primer by organic solvents or O2 ashing. For the fabrication of a LSI-integrated tactile sensor, we used ProTEK PSB with a low temperature oxide underlayer. This combination solves both side etching problem for ProTEK PSB and pinhole problem for low temperature oxide, providing the practical alkaline etching mask which can be prepared at low temperature. © 2010 The Institute of Electrical Engineers of Japan.

News Article | December 7, 2015
Site: www.sciencedaily.com

Hitachi, Ltd. and Tohoku University's Advanced Institute for Materials Research have developed a basic technology to reduce the internal resistance of the all-solid-state lithium ion battery using a complex hydride as a solid electrolyte.

News Article | October 23, 2015
Site: phys.org

Researchers at Tohoku University's Advanced Institute for Materials Research (AIMR) have carried out a collaborative study aimed at precisely controlling phase transformations with high spatial precision, which represents a significant step forward in realizing new functionalities in confined dimensions.

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