Papers - 2009

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[2009_01]

Study of the surface morphology of platinum thin films on powdery substrates prepared by the barrel sputtering system

Akira Taguchi, Mitsuhiro Inoue, Chikako Hiromi, Masaaki Tanizawa, Tomohito Kitami, Takayuki Abe

Vacuum 83 (2009) 575-578

[2009_02]

Surface coating of microparticles with tungsten carbide by using the barrel sputtering system

Satoshi Akamaru, Hironari Yamamoto, Takayuki Abe

Vacuum 83 (2009) 633-636

[2009_03]

Physical and electrochemical properties of Pt-Ru/C samples prepared on various carbon supports by using the barrel sputtering system

Mitsuhiro Inoue, Satoshi Akamaru, Akira Taguchi, Takayuki Abe

Vacuum 83 (2009) 658-663

[2009_04]

Hydrogen-induced magnetic and structural transformations of GdCu

Masanori Hara, Naomi Hatakeyama, Satoshi Akamaru, Kuniaki Watanabe, Katsuhiko Nishimura, Katsunori Mori, Masao Matsuyama

Journal of Magnetism and Magnetic Materials 321 (2009) 423-428

[2009_05]

Special issue -The Way to Know Tritium Behavior-
3.The Way to Know Tritium Distribution on the Surface and in the Bulk of Materials (written in Japanese)

T.Tanabe, M.Matsuyama, Y.Oya, S.Nagata, K.Ochiai

Journal of Plasma and Fusion Research Vol.85, No.1 (2009) 13-22

[2009_06]

Special issue -The Way to Know Tritium Behavior-
4.The Way to Know Tritium Retention in Materials (written in Japanese)

Y.Oya, Y.Torikai

Journal of Plasma and Fusion Research Vol.85, No.1 (2009) 23-27

[2009_07]

Special issue -The Way to Know Tritium Behavior-
6.The Way to Know Tritium Transfer Process in Gaseous and Liquid Phases (written in Japanese)

S.Fukada, Y.Hatano, M.Hara

Journal of Plasma and Fusion Research Vol.85, No.1 (2009) 31-35

[2009_08]

Special issue -The Way to Know Tritium Behavior-
8.Conclusion (written in Japanese)

M.Matsuyama

Journal of Plasma and Fusion Research Vol.85, No.1 (2009) 41-42

[2009_09]

CO₂methanation property of Ru nanoparticle-loaded TiO₂prepared by a polygonal barrel-sputtering method

Takayuki Abe, Masaaki Tanizawa, Kuniaki Watanabe, Akira Taguchi

Energy & Environmental Science, 2009, 2, 315-321

[2009_10]

Temperature driven hydrogen-induced disproportionation of Zr₂Cu

Masanori Hara, Yukiko Hayashi, Kuniaki Watanabe

Journal of Alloys and Compounds 487 (2009) 489-493

[2009_11]

Correlation between hydrogen distribution in V-4Cr-4Ti alloy and impact strength

Y. Hatano, H. Hommaa, T. Sakamura, H. Saitoh, T. Nagasaka, T. Muroga, M. Matsuyama

Journal of Nuclear Materials 386-388 (2009) 569-571

[2009_12]

Studies on Chemical of High Concentration Tritium Water and Organic Comcentration Tritium Water and Organic Compounds of Tritium from Viewpoint of the Tritium Confinement

YAMANISHI Toshihiko, HAYASHI Takumi, IWAI Yasunori, ISOBE Kanetshugu, HARA Masanori, SUGIYAMA Takahiko, OKUNO Kenji

Journal of Plasma Fusion Research. Vol.85, No.10 (2009) 716-725

[2009_13]

Tritium Permeation, Contamination and Decontamination

HATANO Yuji, TORIKAI Yuji, OYA Yasuhisa, ODA Takuji, TANAKA Satoru, NAKAMURA Hirohumi, ASAKURA Yamato, OHUCHI Hiroko

Journal of Plasma Fusion Research. Vol.85, No.10 (2009) 726-735

[2009_14]

CO oxidation on non-alloyed Pt and Ru electrocatalysts prepared by the polygonal barrel-sputtering method

Mitsuhiro Inoue, Toshiharu Nishimura, Satoshi Akamaru, Akira Taguchi, Minoru Umeda and Takayuki Abe

Electrochimica Acta Volume 54, Issue 21(2009) 4764-4771

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[2009_01]

Vacuum 83 (2009) 575-578

 The transition of Pt from a nanoparticle to a film on SiO₂ particles modified by the sputtering system with barrel-type powder sample holder(the barrel sputtering system). X-ray diffraction(XRD) and scanning electron microscopy(SEM) measurements reveal that the Pt nanoparticles grow in size with an increase in the duration of sputter deposition.The morphology of Pt changes from highly dispersed nanoparticles to a worm-like structure followed by a continuous Pt film, depending on the amount of Pt modified. Transmission electron microscopy(TEM) measurements reveal that the thin Pt film in the worm-like structure has a uniform thickness of approximately 2.6 nm, indicating film growth in a two-domensional mode followed by an island mode.

Key words: Barrel sputtering system, Surface coating, Environment friendly process

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[2009_02]

Vacuum 83 (2009) 633-636

 We studied the coating of microparticles with tungsten carbide using a sputtering system with barrel-type powder sample holder(the barrel sputtering system). In order to find suitable sputtering conditions using the system, tungsten carbide was coated on a glass plate under various desired methane fractions, total pressures and RF powers. According to the XRD analysis on the fabricated films, the desired parameter is attained at a methane fraction of 5%, a total pressure of 1.5 Pa, and an RF power of 100 W. Surface coating of polymer microparticles with a WC layer was performed under this condition. Scanning electron microscope and energy-dispersion X-ray spectrum measurement show that the surface of the microparticle is uniformly coated with a thin WC layer.

Keywords: barrel sputtering system, coating, tungsten carbide, powder

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[2009_03]

Vacuum 83 (2009) 658-663

 The present study investigated physical and electrochemical properties of carbon-supported Pt-Ru alloy (Pt-Ru/C) samples prepared on various carbon supports by using a sputtering system with barrel-type powder sample holder(the barrel sputtering system). For this system, the deposited Pt-Ru nano-particles had uniform size of less than 4 nm and homogenerous atomic ratios of Pt and Ru of ca. 50:50 at.% independent of a specific surface area of the carbon support. Further, the electrochemical properties of the prepared samples obtained from CO stripping voltammetry were almost identical. These were completely different from the result for wet process showing that the physical and electrochemical propeties of samples prepared by an impregnation method changed with the specific surface area of the carbon support.

Key words: barrel sputtering system, polymer electrolyte fuel cells(PEFCs), anode electrocatalyst, physical and electrochemical properties, specific surface area of carbon support

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[2009_04]

Journal of Magnetism and Magnetic Materials 321 (2009) 423-428

 The magnetization of GdCu induced by hydrogen uptake was measured within the temperature range of 4.2 to 300 K, occurring phase changes were followed by X-ray diffraction measurements at ambient temperature. The prepared GdCu powder of CsCl-type structure readily absorbed hydrogen at ambient temperature, where hydrogen pressure was below 100 kPa. Hydrogenation changed the magnetism of GdCu in a complex manner from an antiferromagnetic-like type to a paramagnetic-like one. The changes in magnetic properties of GdCu by hydrogenation are governed by hydrogen-induced disproportionation. Within the composition range 0 <[H]/[GdCu]<1, GdCu disproportionated according to 2GdCu+H₂→GdH₂+GdCu₂ . The magnetization was evaluated by the expression χ_total=(1-x)χ_GdCu+(x/2)(χ_GdH2+χ_GdCu2). GdCu hydride was not observed. Hydrogenation beyond [H]/[GdCu]> 1 gave rise to the disproportionation of GdCu₂ causing the change in magnetization.

Key words: Gadolinium copper compound; Hydrogen; Disproportionation; Gadolinium hydride

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[2009_05]

Journal of Plasma and Fusion Research Vol.85, No.1 (2009) 13-22

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[2009_06]

Journal of Plasma and Fusion Research Vol.85, No.1 (2009) 23-27

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[2009_07]

Journal of Plasma and Fusion Research Vol.85, No.1 (2009) 31-35

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[2009_08]

Journal of Plasma and Fusion Research Vol.85, No.1 (2009) 41-42

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[2009_09]

Energy & Environmental Science, 2009, 2, 315-321

 Highly dispersed Ru nanoparticles loaded on a TiO₂support (Ru/TiO₂(B)), which affects the hydrogenation of CO₂ to CH₄ (methanation), were prepared by employing a "dry" modification method using a barre-sputtering instrument. The loaded Ru nanoparicles exhibited a narrow particlesize distribution with a mean diameter of ca. 2.5 nm. Methanation of CO₂ on the Ru/Tio₂(B) catalyst produced a lOO% yield at ca. 160℃, which is more than 200℃ below that required for Ru/TiO₂ prepared by a conventional "wet" impregnation method. ln addition, the methanation reaction over Ru/TiO₂(B) proceeded at temperatures as low as room temperature with a reaction rate of 0.04 υmol min^-1g^-1.

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[2009_10]

Journal of Alloys and Compounds 487 (2009) 489-493

  The absorption of hydrogen by Zr₂Cu was studied by the aid of the Zr₂ Cu-H phase diagram elaborated by Kadel and Weiss. It was found that Zr₂Cu hydride was formed at ambient temperature after moderate hydrogen absorption. Hydrogen-induced disproportionation of Zr₂Cu occurred at temperatures exceeding 550 K. The unknown compound of the phase γ reported by Kadel and Weiss was identified as Zr₇Cu₁₀. It was also found that the β phase consisted of ZrCu and Zr hydride instead of Zr₂CuH_{x, x = 1.0-1.4}. The disproportionation behavior was found to follow a different mechanism below and above 973 K. Below 973K the disproportionation was found to proceed by the reaction sequence, Zr₂Cu+H₂→Zr₇Cu₁₀ + ZrH_x +H₂(γ phase) →Zr₁₄Cu₅₁ + ZrH_x +H₂(δ phase), and above 973K via the sequence, Zr₂Cu+H₂→ZrCu + ZrH_x +H₂(β phase) →Zr₇Cu₁₀ + ZrH_x +H₂(δ phase). The difference could be explained by the thermodynamic stability of ZrCu intermetallic compounds.

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[2009_11]

    Distribution of hydrogen isotopes was examined by tritium radioluminography using imaging plates for specimens of a V-4Cr-4Ti alloy prepared from two different plates fabricated with cold rolling under two different conditions (93% and 96% reduction in thickness) and recrystallization annealing. Influence of hydrogen on impact strength was also studied. Radioluminographs showed that tritium was concentrated in band-like regions where Ti(C,N,O) precipitates were densely distributed. The extent of tritium accumulation in the band-like regions and their shapes, however, were different between the two types of specimens; the band-like regions were thinner and more elongated, and the trapping effects of precipitates was smaller for the specimen prepared with higher extent of cold working. On the other hand, this type of specimen showed lower susceptibility to hydrogen embrittlement. These observations indicated that precipitate distribution prepared with higher extent of cold working is preferable to provide better durability against hydrogen embrittlement.

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[2009_12]

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[2009_13]

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[2009_14]

    The CO oxidation on non-alloyed Pt and Ru electrocatalysts prepared by the polygonal barrel-sputtering method was investigated. Samples were prepared by sputtering Pt and Ru separately at room temperature. From the X-ray diffraction (XRD) measurement of the sample prepared on a SiO₂ glass plate, it was found that the sputtered metals are non-alloyed. Subsequently, the non-alloyed Pt and Ru electrocatalysts were prepared by the polygonal barrel-sputtering method using carbon powder as a support. The XRD patterns of these samples showed a single and very broad peak supporting the hypothesis of the non-alloyed Pt and Ru. No separate Ru reflections were visible, which could be attributed to Ru particle sizes smaller than 4 nm, as obtained by transmission electron microscopy (TEM). CO oxidation on the non-alloyed Pt and Ru electrocatalysts were evaluated by CO stripping voltammetry. This measurement revealed that the lower peak potential of CO oxidation varies, depending on the Pt content and the sputtering order. In addition, it was assumed that the CO oxidation reaction site for non-alloyed Pt and Ru electrocatalyst has a limited area including direct contact sites between the Pt and Ru particles.

Keywords: CO oxidation; Non-alloyed Pt and Ru electrocatalyst; Polymer electrolyte fuel cells; Anode catalyst; Polygonal barrel-sputtering method