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Nagata, Shinji*; Fujita, Haruka*; Inoue, Aichi; Yamamoto, Shunya; Tsuchiya, Bun*; Shikama, Tatsuo*
Nuclear Instruments and Methods in Physics Research B, 268(19), p.3151 - 3154, 2010/10
Times Cited Count：3 Percentile：28.83(Instruments & Instrumentation)A tungsten tri-oxide (WO
) film covered with a thin catalyst layer is one of the candidates for hydrogen sensing devices that show a reversible coloration under hydrogen exposure. While the injection of the cations and/or the formation of the oxygen vacancies can be responsible for the coloration of the film, the mechanism of the gasochromic phenomenon is not fully understood. In the present work, the changes of the optical properties in the WO film by ion irradiation were investigated to clarify the relation between the coloration and oxygen vacancies. WO films of 300-500 nm thicknesses were deposited on SiO
substrates by magnetron sputtering. Oxygen ions at energies between 200 and 800 keV were irradiated to the WO films. The optical absorption of the film was measured in the wavelengths between 190 and 1000 nm. The results show that the change of optical-absorption coefficient in WO films depends on both electronic and nuclear stopping powers.
To, Kentaro; Shikama, Tatsuo*; Katsui, Hirokazu*; Nagata, Shinji*; Tsuchiya, Bun*; Yamauchi, Michinori*; Nishitani, Takeo
Journal of Nuclear Materials, 386-388, p.1027 - 1029, 2009/04
Times Cited Count：4 Percentile：30.49(Materials Science, Multidisciplinary)Fluorescence and long-lasting emission properties of two types of Long-lasting phosphors (LLPs), SrAlO
:Eu
,Dy
and SrAl
O
:Eu,Dy, were examined under 14-MeV neutron irradiation. The fluorescent spectra of the LLPs have characteristic peaks due to their dopants and the fluorescent intensity of SrAlO:Eu,Dy shows good radiation resistance for the neutrons fluence up to 10
n/m
. Long-lasting emissions are exhibited after neutron irradiation, and the emission spectra have one peak due to Eu. Further, it is found that there is an optimum neutron fluence at which the longest decay time is obtained.
Nagata, Shinji*; Katsui, Hirokazu*; Tsuchiya, Bun*; Inoue, Aichi; Yamamoto, Shunya; To, Kentaro; Shikama, Tatsuo*
Journal of Nuclear Materials, 386-388, p.1045 - 1048, 2009/04
Times Cited Count：14 Percentile：66.94(Materials Science, Multidisciplinary)no abstracts in English
Nagata, Shinji*; Sasase, Masato*; Takahiro, Katsumi*; Tsuchiya, Bun*; Inoue, Aichi; Yamamoto, Shunya; Shikama, Tatsuo*
Nuclear Instruments and Methods in Physics Research B, 267(8-9), p.1514 - 1517, 2009/03
Times Cited Count：9 Percentile：53.48(Instruments & Instrumentation)In this study, effects of the ion implantation on the phase transformation and nano-crystalline formation were examined in Zr-based metallic glasses. Samples were 2 mm thick plates and thin films of Zr
Al
Ni
Cu
prepared by casting in a copper mold and by using RF magnetron sputtering, respectively. Ions of Mg, P, Au and Bi with 100-500 keV were implanted in the samples up to 2 
10
ions/cm at room temperature. Nano-crystalline structure was found in implanted samples by TEM observation, while the long-range order in the structure was not found for the X-ray diffraction patterns. The electron diffraction patterns indicated the formation of fcc-ZrCu in the P, Au, and Bi implanted region. Changes of the binding energy of the core level electron and valence band structure suggested the formation of Au-Zr or Au-Cu alloys in the Au ion implanted region.
-phase zirconium hydrides and deuteridesTsuchiya, Bun*; Yasuda, Ryo; Teshigawara, Makoto; Konashi, Kenji*; Nagata, Shinji*; Shikama, Tatsuo*; Yamawaki, Michio*
Journal of Nuclear Materials, 376(1), p.60 - 65, 2008/05
Times Cited Count：2 Percentile：16.99(Materials Science, Multidisciplinary)Distributions of hydrogen isotope concentrations in e-phase zirconium hydrides and deuterides (-ZrHx and -ZrDx: 1.8 
x 2.0) were investigated by neutron radiography (NRG). The NRG images of the thermal neutron transmission and backscattering revealed hydrogen concentration dependence and isotope differences. The thermal neutron mass attenuation coefficients in relation to the hydrogen isotope concentrations were determined from the transmission NRG images. The results showed the isotope effects of the thermal neutron mass attenuation coefficients for -ZrHx to be about 6-9 times higher than those for -ZrDx. The neutron scattering processes for transmission and backscattering NRG images of -ZrHx and -ZrDx were also analyzed using a general Monte Carlo neutron-particle transport (MCNP) code.
Nagata, Shinji*; Inoue, Aichi; Yamamoto, Shunya; Tsuchiya, Bun*; Takano, Katsuyoshi; To, Kentaro*; Shikama, Tatsuo*
Journal of Alloys and Compounds, 446-447, p.558 - 561, 2007/10
Times Cited Count：20 Percentile：69.88(Chemistry, Physical)The effect of the composition of non-stoichiometric WO films on the gasochromic coloration are investigated. The films are prepared by a reactive RF magnetron sputtering with varying oxygen partial pressure. To determine the quantitative composition of deposited films, Rutherford backscattering spectroscopy (RBS) and Elastic recoil detection (ERD) are employed. Gasochromic coloration of the films coated with Pd catalyst is examined by optical transmission in hydrogen gas. O/W atomic ratio of the films increases from 0.25 to 3.0 with increasing the oxygen partial pressure in the sputtering gas. H/W ratio increases up to 0.7 with increasing the O/W ration. As regards gasochromic coloration, the film with O/W atomic ratio of 3.0 shows superior coloration performance comparing with that of less than 3.0. Therefore, it is assumed that the good gasochromic coloration of tungsten oxide films is realized by near-stoichiometric WO. In addition, gasochromic coloration state, increasing of hydrogen concentration in WO films is observed. It indicates that gasochromic coloration of WO is relate to formation of HWO structure.
To, Kentaro*; Shikama, Tatsuo*; Nagata, Shinji*; Tsuchiya, Bun*; Yamauchi, Michinori; Nishitani, Takeo
Journal of Nuclear Materials, 367-370(2), p.1128 - 1132, 2007/08
Times Cited Count：6 Percentile：42.5(Materials Science, Multidisciplinary)no abstracts in English
Nagata, Shinji*; Yamamoto, Shunya; Inoue, Aichi*; Tsuchiya, Bun*; To, Kentaro*; Shikama, Tatsuo*
Journal of Nuclear Materials, 367-370(2), p.1009 - 1013, 2007/08
Times Cited Count：32 Percentile：88.39(Materials Science, Multidisciplinary)no abstracts in English
Inoue, Aichi; Nagata, Shinji*; To, Kentaro*; Tsuchiya, Bun*; Yamamoto, Shunya; Shikama, Tatsuo*
Journal of Nuclear Materials, 367-370(2), p.1112 - 1116, 2007/08
Times Cited Count：5 Percentile：37.19(Materials Science, Multidisciplinary)The ion-induced luminescence behavior has been investigated for Cr-doped alumina (ruby, 
-AlO: 0.5 wt% Cr) under MeV region H and He ion irradiation. The initial yield of the R-line luminescence (693 nm) increased proportionally to the projected range of the incident H ions, indicating that the ion- induced luminescence efficiency for an H ion was constant with independence of the electronic energy loss. However, the He induced luminescence yield was not directly related to either the projected range or the incident energy, corresponding that the efficiency decreased with increasing the electronic energy loss. The reduction of R-line yields by the ion irradiation was adequately explained by decreasing R-line luminescence centers.
Nagata, Shinji*; Konishi, Yoshitada*; Tsuchiya, Bun*; To, Kentaro*; Yamamoto, Shunya; Takahiro, Katsumi*; Shikama, Tatsuo*
Nuclear Instruments and Methods in Physics Research B, 257(1-2), p.519 - 522, 2007/04
Times Cited Count：7 Percentile：50.06(Instruments & Instrumentation)Effects of MeV ion irradiation on electrical characteristics of perfluorosulphonic polymer membrane have been studied. The DC electrical conductivity in dry condition increased of three orders of magnitude as a consequence of irradiation with MeV region H and He ion irradiation at a fluence of 2 10
ions/cm. The optical absorption in the ultra-violet region increased in the ion irradiated membrane due to the formation of fluorocarbon and peroxy radicals. The ion irradiation may form fluorocarbon and peroxy compounds and improve the transport property of protons in the membrane.
Nagata, Shinji*; Higashi, Seijiro*; Tsuchiya, Bun*; To, Kentaro*; Shikama, Tatsuo*; Takahiro, Katsumi*; Ozaki, Koichi*; Kawatsura, Kiyoshi*; Yamamoto, Shunya; Inoue, Aichi
Nuclear Instruments and Methods in Physics Research B, 257(1-2), p.420 - 423, 2007/04
Times Cited Count：16 Percentile：72.04(Instruments & Instrumentation)Structural modification and primary precipitates in the ZrAlNiCu alloy films (50-100 
m thickness) caused by radiation with 300-500 keV H, Ag, Cu and Au ions has been studied. The results of XRD indicated that a metastable primary phase was formed in the alloy by the heat treatment after ion irradiation, but no difference was observed just after the ion irradiation at room temperature. Furthermore, higher incident Au ion fluence effectively suppressed thermal precipitation of the ZrNi type crystalline phase in the alloy. The deposited energy dependence of the precipitation behavior indicated an increase of the nucleation sites by the implanted metal atoms, simultaneously with a decrease of the growth rate by higher energy deposition density.
Nagata, Shinji*; Yamamoto, Shunya; Inoue, Aichi; Tsuchiya, Bun*; To, Kentaro*; Takano, Katsuyoshi; Yoshikawa, Masahito; Shikama, Tatsuo*
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 148, 2007/02
no abstracts in English
Takahiro, Katsumi*; Oizumi, Shinnosuke*; Terai, Atsushi*; Kawatsura, Kiyoshi*; Tsuchiya, Bun*; Nagata, Shinji*; Yamamoto, Shunya; Naramoto, Hiroshi; Narumi, Kazumasa; Sasase, Masato*
Journal of Applied Physics, 100(8), p.084325_1 - 084325_6, 2006/10
Times Cited Count：28 Percentile：68.36(Physics, Applied)X-ray photoelectron spectroscopy (XPS) has been applied for size estimation of Au clusters formed by ion implantation into glassy carbon. The 4f and 5d XPS spectra reveal the presence of the cluster 0.7-2.5nm in diameter, depending on the Au concentration. The elationship between XPS 4f-binding energy shift and 5d splitting is determined for the Au clusters embedded in the carbon and found to be significantly different from the previous data for the ones supported on a carbon substrate. We suppose that this difference results from the effect of the environment around a cluster on Coulomb charging during photoemission at the final state.
-ray and 14 MeV neutron irradiationTo, Kentaro*; Shikama, Tatsuo*; Nagata, Shinji*; Tsuchiya, Bun*; Yamauchi, Michinori; Nishitani, Takeo
Measurement Science and Technology, 17(5), p.955 - 959, 2006/05
Times Cited Count：6 Percentile：43.68(Engineering, Multidisciplinary)The effect of photobleaching on radiation-induced transmission loss of fused-silica-core optical fibres was examined under 
Co -ray and 14 MeV neutron irradiation. In the visible wavelength range, the radiation-induced transmission loss could be reduced by photobleaching under both types of irradiation. It is considered that the number of radiation-induced defects such as E' centre and NBOHC that cause optical absorption was reduced by photobleaching. For using optical fibres in the visible wavelength range as light guides or image guides, photobleaching is an effective technique to improve their radiation resistance. However, a so-called microbending loss is induced by radiation in the entire wavelength range. The loss response to photobleaching was different under -ray and fast-neutron irradiation. The loss under the -ray irradiation increased due to photobleaching, while that under the fast-neutron irradiation decreased. It is considered that there are multiple reasons for the radiation-enhanced microbending loss. In general, it is concluded that the photobleaching technique is effective in improving the radiation resistance of fused-silica-core optical fibres under neutron and moderate flux radiation environments.
Takahiro, Katsumi*; Terai, Atsushi*; Kawatsura, Kiyoshi*; Naramoto, Hiroshi; Yamamoto, Shunya; Tsuchiya, Bun*; Nagata, Shinji*; Nishiyama, Fumitaka*
Japanese Journal of Applied Physics, Part 1, 45(3A), p.1823 - 1825, 2006/03
Times Cited Count：2 Percentile：8.72(Physics, Applied)It is found that the surface charging during Rutherford backscattering spectrometry (RBS) of insulating sapphire samples enables us to measure the charge-state distribution of probing ions backscattered at the sapphire surface. For Cu/Au-deposited AlO samples, two components, higher and lower-energy ones, were resolved on both Cu and Au peaks in the RBS random spectrum. For single-crystalline AlO samples, a double-peak structure was clearly observed on both Al and O surface peaks in the RBS aligned spectrum. The charge-state distribution can be obtained from the intensity of each component. The results obtained here are compared with previous data for the equilibrium charge-state distribution.
Nagata, Shinji*; Yamamoto, Shunya; Tokunaga, Kazutoshi*; Tsuchiya, Bun*; To, Kentaro*; Shikama, Tatsuo*
Nuclear Instruments and Methods in Physics Research B, 242(1-2), p.553 - 556, 2006/01
Times Cited Count：7 Percentile：47.51(Instruments & Instrumentation)no abstracts in English
Tsuchiya, Bun*; Morita, Kenji*; Yamamoto, Shunya; Nagata, Shinji*; Otsu, Naofumi*; Shikama, Tatsuo*; Naramoto, Hiroshi
Journal of Nuclear Materials, 313-316, p.274 - 278, 2003/03
Times Cited Count：1 Percentile：10.88(Materials Science, Multidisciplinary)no abstracts in English
Tsuchiya, Bun*; Teshigawara, Makoto; Nagata, Shinji*; Konashi, Kenji*; Yasuda, Ryo; Nishino, Yasuharu; Nakagawa, Tetsuya*; Yamawaki, Michio*
Nuclear Instruments and Methods in Physics Research B, 190(1-4), p.699 - 703, 2002/05
Times Cited Count：10 Percentile：54.86(Instruments & Instrumentation)Practicability of Elastic Recoil Detection (ERD) and Neutron Radiography (NRG) methods for hydrogen concentration in titanium hydrides (d-TiHx : 1.6<x<2.0) is investigated. In ERD methods, the hydrogen concentration in the surface of TiHx is recognized. In NRG method, the hydrogen concentration over the balk was confirmed. These results show that both methods are effective means for estimating the hydrogen concentration in hydride materials.
Yamamoto, Shunya; Naramoto, Hiroshi; Narumi, Kazumasa; Tsuchiya, Bun*; Aoki, Yasushi; Kudo, Hiroshi*
Nuclear Instruments and Methods in Physics Research B, 134(3-4), p.400 - 404, 1998/00
Times Cited Count：4 Percentile：40.65(Instruments & Instrumentation)no abstracts in English
Tsuchiya, Bun*; Yamamoto, Shunya; Narumi, Kazumasa; Aoki, Yasushi*; Naramoto, Hiroshi; Morita, Kenji*
Thin Solid Films, 335(1-2), p.134 - 137, 1998/00
Times Cited Count：2 Percentile：16(Materials Science, Multidisciplinary)no abstracts in English
