Influence of surface oxide layer on deuterium molecule desorption from V(001) surface

Teraoka, Yuden; Tode, Mayumi*; Harries, J.; Yoshigoe, Akitaka

Denki Gakkai Rombunshi, C, 134(4), p.473 - 478, 2014/04

https://doi.org/10.1541/ieejeiss.134.473

A Chemical-state-specific study of the composition of the natural oxide layer of VCrTi

Harries, J.; Teraoka, Yuden; Tode, Mayumi; Yoshigoe, Akitaka

Applied Physics Express, 5(3), p.031802_1 - 031802_3, 2012/03

https://doi.org/10.1143/APEX.5.031802

Structural and valence changes of europium hydride induced by application of high-pressure H

Matsuoka, Takahiro*; Fujihisa, Hiroshi*; Hirao, Naohisa*; Oishi, Yasuo*; Mitsui, Takaya; Masuda, Ryo; Seto, Makoto*; Yoda, Yoshitaka*; Shimizu, Katsuya*; Machida, Akihiko; et al.

Physical Review Letters, 107(2), p.025501_1 - 025501_4, 2011/07

https://doi.org/10.1103/PhysRevLett.107.025501

Europium-hydride EuH exposed to high-pressure H conditions has been found to exhibit structural and valence changes, (=2, divalent) 63/ (=2, 7.2-8.7 GPa) 4/ (2, 8.7-9.7 GPa) 4/ (2, 9.7 GPa-, trivalent). Having trivalent character and distorted cubic fcc structure, the 4/ structure is the -phase which has been commonly observed for other rare-earth metal hydrides. Our study clearly demonstrates that EuH is no longer an "irregular" member of the rare earth metal hydrides.

Thermal degradation analysis of deuterium-ion-implanted VCrTi using synchrotron radiation photoelectron spectroscopy

Tode, Mayumi; Harries, J.; Teraoka, Yuden; Yoshigoe, Akitaka

Denki Gakkai Rombunshi, C, 130(10), p.1819 - 1820, 2010/10

https://doi.org/10.1541/ieejeiss.130.1819

In order to study the thermal degradation process of the hydrogen storage materials surface layer and the thermal desorption of hydrogen property, we have used high-resolution synchrotron radiation X-ray photoelectron spectroscopy. The experiments were performed at the JAEA soft X-ray beamline BL23SU at SPring-8, using the "SUREAC2000" surface reaction analysis apparatus. Spectra were recorded for two samples (VCrTi) covered with native oxide layers, one of which was implanted with deuterium ions. For the un-implanted sample, the oxide layer changes dramatically between 373 K and 473 K, for the deuterium-implanted sample, the change occurs between 473 K and 573 K. The implantation of deuterium leads to a stabilization (of approximately 100 K) of the surface oxide layer.

Correlation between the averaged internal structure and the coercive force of neodymium-iron-boron (Nd-Fe-B) sintered magnets investigated by small-angle neutron scattering

Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*

Proceedings of 21st International Workshop on Rare-Earth Permanent Magnets and their Applications (REPM 2010), p.161 - 164, 2010/08

We performed small-angle neutron scattering (SANS) measurements of Nd-Fe-B sintered magnets to get information on the averaged internal microstructure of Nd-Fe-B sintered magnets including the interfacial structure which is a key parameter to achieve a high-coercivity Dy-free Nd-Fe-B sintered magnet. SANS patterns from the Nd-Fe-B sintered magnets measured with a two-dimensional detector of a small-angle neutron scattering spectrometer SANS-J-II in the research reactor JRR-3 were sensitive to the sintering and annealing condition of the samples. These results indicate that the SANS measurement is a promising tool to investigate the correlation between the coercivity and the internal microstructure of Nd-Fe-B sintered magnets.

Conceptual design of experimental equipment for large-diameter NTD-Si

Yagi, Masahiro; Watanabe, Masanori; Oyama, Koji; Yamamoto, Kazuyoshi; Komeda, Masao; Kashima, Yoichi; Yamashita, Kiyonobu

Applied Radiation and Isotopes, 67(7-8), p.1225 - 1229, 2009/07

https://doi.org/10.1016/j.apradiso.2009.02.018

A Combined method of small-angle neutron scattering and neutron radiography to visualize water in an operating fuel cell over a wide length scale from nano to millimeter

Iwase, Hiroki; Koizumi, Satoshi; Iikura, Hiroshi; Matsubayashi, Masahito; Yamaguchi, Daisuke; Maekawa, Yasunari; Hashimoto, Takeji

Nuclear Instruments and Methods in Physics Research A, 605(1-2), p.95 - 98, 2009/06

https://doi.org/10.1016/j.nima.2009.01.165

We constructed an in-situ and simultaneous observation method as a result of combination between ultra-small-angle neutron scattering and neutron imaging (radiography). With this novel technique, we are able to visualize water distribution or transportation, occurring from micro to macro length scales in a polymer electrolyte fuel cell (PEFC). At a sample position of SANS-J-II at JRR-3, we installed a neutron imaging camera in order to construct an in-situ and simultaneous observation method by USANS and neutron imaging with monochromatized cold neutrons. In addition, in order to selectively observe MEA in a running PEFC by using the in-situ and simultaneous observation method, we need to replace carbon separators which cause strong small-angle scattering as a noise. To reduce this strong background, we replaced the carbon separators with the aluminium ones. As a result, the background scattering was minimized (1/10) as compared to before.

Synchrotron radiation photoemission spectroscopy for native oxide layer on Vanadium and VCrTa

Teraoka, Yuden; Yoshigoe, Akitaka; Harries, J.

Journal of Surface Analysis, 15(3), p.303 - 306, 2009/03

https://doi.org/10.1384/jsa.15.303

In order to study correlation between oxide layers on hydrogen storage metals such as V(111), polycrystalline Vanadium, and VCrTa alloy and hydrogen desorption temperature, the surfaces covered by native oxides have been analyzed by photoemission spectroscopy using soft X-ray synchrotron radiation. Depth analyses of the oxide layers were performed by changing synchrotron radiation energy to estimate the oxide thickness. The native oxide layer was disappeared by thermal annealing up to 713 K for the V(111) surface. The oxide layers of the poly V and the VCrTa alloy, however, were remained even at 873 K. Although the oxides of V and Cr were disappeared, Ta oxides were remained. The re-arrangement of oxidation took place in the oxide layer of VCrTa alloy by thermal annealing. The oxidation of Ta controlled oxide thickness in the VCrTa alloy. The formation of an artificial oxide layer could be controlled using supersonic oxygen molecular beams.

Conceptual design of irradiation experimental device for 12 inch NTD-Si ingot in JRR-4 (Contract research)

Yagi, Masahiro; Watanabe, Masanori; Oyama, Koji; Komeda, Masao; Yamamoto, Kazuyoshi; Kashima, Yoichi

JAEA-Technology 2008-015, 91 Pages, 2008/03

JAEA-Technology-2008-015.pdf:22.92MB

The irradiation experimental device is designed by surveying analytically an irradiation condition to improve the neutron flux distribution of the radial direction on NTD-Si by using neutron transportation calculation Monte Carlo calculation code MCNP5 in order to develop neutron irradiation technology for the large-diameter silicon to 12 inches diameter at the maximum and an irradiation experiment will be performed in JRR-4. Thus the validity of the design technique of the irradiation device will be confirmed by this experiment. The irradiation experimental device is installed in the side of the core tank outer wall. A 12 inches silicon ingot of 60cm in height is irradiated in a reflector cover which surrounds the silicon ingot for increasing the flux. The silicon ingot is rotated during irradiation in order to require the condition of uniformly distributed thermal neutron flux over whole circumferences. A uniform irradiation condition was achieved by the pass-through core method, in which silicon ingot moved up and down with rotating. The condition was satisfied when silicon was covered with the thermal neutron filter, which is made from aluminum alloy of thickness of 2mm with natural boron element ratio of 1.5%, and was moved in the range from -42mm to 22mm for the center of the reactor core. The deviation of the Si-30 neutron absorption reaction rate was range from -3.2% to +5.3% in the intermediate volume of 40cm height and the neutron absorption reaction ratio of the circumference to the center was within 1.09 in the volume.

Status of neutron transmutation doping method in research reactors

Yamashita, Kiyonobu; Isshiki, Masahiko*; Sagawa, Hisashi; Yamamoto, Kazuyoshi

no journal, , 

no abstracts in English