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Yokohama-shi, Japan

Kuwahara M.,Japan National Institute of Advanced Industrial Science and Technology | Suzuki O.,Japan National Institute of Advanced Industrial Science and Technology | Suzuki O.,ULVAC RIKO Inc. | Yagi T.,Japan National Institute of Advanced Industrial Science and Technology | Taketoshi N.,Japan National Institute of Advanced Industrial Science and Technology
Japanese Journal of Applied Physics

We have measured the temperature dependence of the complex refractive index, specific heat capacity, and thermal conductivity of crystalline Sb-Te alloys and ZnS-SiO2 with various compositions by using a spectroscopic ellipsometer, differential scanning calorimeter, and nanosecond pulsed light heating thermoreflectance system. The temperature range was set from room temperature to several hundred degrees Celsius. The values of these properties are useful for calculating realistic temperatures in memory devices and for designing device structures. © 2013 The Japan Society of Applied Physics. Source

Ito T.,Kanagawa Industrial Technology Center | Kunimatsu M.,Kanagawa Industrial Technology Center | Kaneko S.,Kanagawa Industrial Technology Center | Hirabayashi Y.,Kanagawa Industrial Technology Center | And 3 more authors.

We propose novel electrodes with platinum nanoparticles dispersed on a glassy carbon (Pt-NPs/GC) prepared using a pulsed arc plasma deposition (APD) method. The method could coat Pt-NPs on a base material directly with a single-step process in a very short deposition time. The characteristics of the electrodes were discussed in detail. The detection of hydrogen peroxide was performed as an example for application of the electrodes. The distribution of nanoparticles was controlled easily by the number of pulse. The surface morphology changed with the pulse number and the annealing except for the sample prepared by 5 pulses deposition (APD(5)), implying that the APD(5) remained as NPs after the annealing. Average particle size was 2.7 nm on the Pt-NPs/GC. Catalyst activity for oxidizing hydrogen peroxide per Pt loading was excellent on the Pt-NPs/GC. When the Pt-NPs/GC was used as a detector for hydrogen peroxide on a flow injection analysis, the Pt-NPs/GC showed high sensitivity without deterioration. Oxidation current increased linearly with the concentration of hydrogen peroxide from 10 nM to 100 μM. This fast and easily prepared electrode showed the capability to replace a conventional bulk metal electrode. © 2012 Elsevier B.V. Source

Nakamura Y.,Osaka University | Nakamura Y.,Japan Science and Technology Agency | Isogawa M.,Osaka University | Ueda T.,Osaka University | And 9 more authors.
Nano Energy

Reduction of thermal conductivity κ while preserving high electrical conductivity σ in materials continues to be a vital goal in thermoelectric study for the reuse of exhaust heat energy. In the use of an eco-friendly and ubiquitous element, Si as thermoelectric material, high κ value in bulk Si is the essential bottleneck to achieve high dimensionless figure of merit. This is a motivation for many recent studies on reducing κ in Si, by nanostructuring, e.g., using grains/wires with size smaller than the phonon mean free path. However, κ reduction that can be achieved tends to be saturated presumably due to an amorphous limit. Here, we present a nanoarchitecture for defeating the κ amorphous limit while preserving bulk-like σ. This new nanoarchitecture is an assembly of Si nanocrystals with oriented crystals separated by a 1-monolayer amorphous layer with well-controlled nanoscale shaped interfaces. At these interfaces, novel phonon scattering occurs resulting in κ reduction below the amorphous limit. Preservation of bulk-like σ results from the coherency of the carrier wavefunctions among the oriented nanocrystals separated by the ultrathin amorphous layer. The results will bring environmentally-friendly and low-cost thermoelectric Si material compatible with mature LSI process technology and represent guidelines for optimized thermoelectric nanostructures. © 2014 Elsevier Ltd. Source

Akoshima M.,National Metrology Institute of Japan | Tanaka T.,Sumitomo Metal Technology Ltd. | Endo S.,ULVAC RIKO Inc. | Tetsuya Baba,National Metrology Institute of Japan | And 4 more authors.
Japanese Journal of Applied Physics

Ceramic-based thermal barrier coatings are used as heat and wear shields of gas turbine blades. There is a strong need to evaluate the thermal conductivity of coating for thermal design and use. The thermal conductivity of a bulk material is obtained as the product of thermal diffusivity, specific heat capacity, and density above room temperature in many cases. Thermal diffusivity and thermal conductivity are unique for a given material because they are sensitive to the structure of the material. Therefore, it is important to measure them in each sample. However it is difficult to measure the thermal diffusivity and thermal conductivity of coatings because coatings are attached to substrates. In order to evaluate the thermal diffusivity of a coating attached to the substrate, we have examined the laser flash method with the multilayer model on the basis of the response function method. We carried out laser flash measurements in layered samples composed of a CoNiCrAlY bond coating and a 8YSZ top coating by thermal spraying on a Ni-based superalloy substrate. It was found that the procedure using laser flash method with the multilayer model is useful for the thermal diffusivity evaluation of a coating attached to a substrate. © 2011 The Japan Society of Applied Physics. Source

Xu C.,Ford Motor Company | Yang J.,Ford Motor Company | Pence B.L.,Ford Motor Company | Gath K.,Ford Motor Company | And 5 more authors.
ECS Transactions

A two dimensional (2D) platinum network catalyst on graphitic carbon and amorphous NbOx hybrid support has been synthesized by the Arc Plasma Deposition (APD) method. The 2D platinum structure on the conductive, corrosion resistant amorphous metal oxide significantly increases the catalyst stability under RDE accelerated stress tests. RDE and 5cm2 MEA single cell test results show that the catalyst has higher specific and mass activities than those of conventionally prepared platinum on graphitic carbon (Pt/GC) catalyst. The microstructures of the catalyst were characterized by scanning tunneling microscopy (STM). © The Electrochemical Society. Source

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