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Schnepp Z.,Japan National Institute of Materials Science | Hollamby M.J.,Japan National Institute of Materials Science | Tanaka M.,Station X | Matsushita Y.,Station X | And 2 more authors.
Science and Technology of Advanced Materials

Metal oxide/nitride nanocomposites have many existing and potential applications, e.g. in energy conversion or ammonia synthesis. Here, a hybrid oxide/nitride nanocomposite (anatase/Ti xW 1xN) was synthesized by an ammonia-free sol-gel route. Synchrotron x-ray diffraction, complemented with electron microscopy and thermogravimetric analysis, was used to study the structure, composition and mechanism of formation of the nanocomposite. The nanocomposite contained nanoparticles (<5nm diameter) of two highly intermixed phases. This was found to arise from controlled nucleation and growth of a single oxide intermediate from the gel precursor, followed by phase separation and in situ selective carbothermal nitridation. Depending on the preparation conditions, the composition varied from anatase/Ti xW 1xN at low W content to an isostructural mixture of Ti-rich and W-rich Ti xW 1xN at high W content. In situ selective carbothermal nitridation offers a facile route to the synthesis of nitride-oxide nanocomposites. This conceptually new approach is a significant advance from previous methods, which generally require ammonolysis of a pre-synthesized oxide. © 2012 National Institute for Materials Science. Source

Maesaka H.,RIKEN | Ego H.,RIKEN | Inoue S.,SPring 8 Service Co. | Matsubara S.,Japan Synchrotron Radiation Research Institute | And 3 more authors.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

We have developed and constructed a C-band (4.760 GHz) rf cavity beam position monitor (RF-BPM) system for the XFEL facility at SPring-8, SACLA. The demanded position resolution of the RF-BPM is less than 1μm, because an electron beam and x-rays must be overlapped within 4μm precision in the undulator section for sufficient FEL interaction between the electrons and x-rays. In total, 57 RF-BPMs, including IQ demodulators and high-speed waveform digitizers for signal processing, were produced and installed into SACLA. We evaluated the position resolutions of 20 RF-BPMs in the undulator section by using a 7 GeV electron beam having a 0.1 nC bunch charge. The position resolution was measured to be less than 0.6μm, which was sufficient for the XFEL lasing in the wavelength region of 0.1 nm, or shorter. © 2012 Elsevier B.V. Source

Kobayashi K.,Japan National Institute of Materials Science | Matsushita Y.,Japan National Institute of Materials Science | Tanaka M.,Japan National Institute of Materials Science | Katsuya Y.,SPring 8 Service Co. | And 2 more authors.
Solid State Ionics

In this study, we determined the crystallographic nature and electrical transport properties of Nd 9.20(SiO 4) 6O 1.8 and (La 0.46Nd 0.54) 9.33(SiO 4) 6O 2, which are defect-containing oxyapatites. The intensity data measured by synchrotron powder X-ray diffraction were analyzed by a Rietveld method. From the total conductivity data, the oxygen partial pressure region where the oxygen ionic conductivity (σ O 2-) predominates was determined to narrow down owing to the substitution of neodymium ions. A comparison of various solid solutions under similar temperature conditions ranging from 873 K to 1273 K showed that the σO 2- values were lowest for (La 0.46Nd 0.54) 9.33(SiO 4) 6O 2 samples. The activation energy of the oxygen ionic conductivity increased with an increasing neodymium content. © 2012 Elsevier B.V. Source

Guo Y.F.,Japan International Center for Materials Nanoarchitectonics | Shi Y.G.,Transformative Research Project on Iron Pnictides TRIP | Yu S.,Japan National Institute of Materials Science | Belik A.A.,Japan International Center for Materials Nanoarchitectonics | And 12 more authors.
Physical Review B - Condensed Matter and Materials Physics

We observed a large decrease in Tc by no more than 3 at.% of Zn doped into the Tc -optimized superconductor LaFeAsO0.85 (Tc =26 K), confirmed by measurements of electrical resistivity, magnetic susceptibility, specific heat, Mössbauer spectroscopy, Hall coefficient, and an electron probe microanalysis. The rate ∼9 K/% is remarkably higher than others achieved by nonmagnetic impurities. The T c suppression is likely due to pair breaking caused by scattering associated with the highly localized electronic state of Zn in the Fe 2As2 layer. If this is true, the present result well accords with the theoretical prediction that suggests a sign reversal s -wave pairing model for the Fe-pnictide superconductors. © 2010 The American Physical Society. Source

Kagoshima Y.,University of Hyogo | Takano H.,University of Hyogo | Takeda S.,SPring 8 Service Co.
Applied Physics Letters

An inclined-incidence quasi-Fresnel lens made of acrylic resin has been developed for prefocusing in synchrotron radiation x-ray beamlines. By inclining the lens, the grating aspect ratio is large enough for x-ray use. As it operates in transmission mode with negligible beam deflection and offset, little additional equipment is needed to introduce it into existing beamlines. It is fabricated by sheet-press forming, enabling inexpensive mass production. The prototype was able to focus a 730-μm-wide beam to a width of 80 μm with a photon flux density gain of 5.6 at an x-ray energy of 10 keV. © 2012 American Institute of Physics. Source

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