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Takano, Katsuyoshi; Inoue, Aichi; Yamamoto, Shunya; Sugimoto, Masaki; Sugiyama, Akira; Yoshikawa, Masahito
Transactions of the Materials Research Society of Japan, 32(3), p.673 - 676, 2007/09
The deposition of tungsten oxide on the sheet of polyethylene terephthalate or polyvinylindene chloride was performed by sputtering method. It was found that the color of the sheets changes within few minuets to expose 0.1 vol.% diluted hydrogen, so as to be able to confirm the change by viewing. The sheets can be produced with low cost, and are useful as convenient sheet-type hydrogen sensors for the utilization of hydrogen in fuel cell as a clean energy source.
Takigami, Machiko*; Amada, Haruyo*; Nagasawa, Naotsugu; Yagi, Toshiaki; Kasahara, Takamitsu*; Takigami, Shoji*; Tamada, Masao
Transactions of the Materials Research Society of Japan, 32(3), p.713 - 716, 2007/09
Carboxymethylcellulose (CMC) gel was formed by addition of acid to CMC (CMC-acid gel). Gel fraction (weight of insoluble part/initial CMC weight) was calculated after removing uncrosslinked CMC by immersing the CMC-acid gel in water. It increased with acid concentration. Mechanism of CMC-acid gel formation was elucidated by aggregation of CMC molecules as the result of replacement of sodium in carboxyl group with hydrogen. Gels could be prepared by three different procedures; (1) mixing CMC and acid, (2) immersion of CMC or 
-irradiated CMC pastes in acid, and (3) -irradiation of CMC-acid gel. Gels with different elasticity and hardness were prepared changing degree of substitution of CMC, molar mass of CMC, species of acid, concentrations of acid and CMC, and application of -irradiation.
Takahashi, Masamitsu; Kaizu, Toshiyuki; Mizuki, Junichiro
Transactions of the Materials Research Society of Japan, 32(1), p.209 - 214, 2007/03
Molecular beam epitaxial (MBE) growth of InAs/GaAs(001) quantum dots was investigated by grazing-incidence X-ray diffraction using a diffractometer integrated with an MBE apparatus, which was installed on beamline 11XU at SPring-8. Use of synchrotron radiation and a two-dimensional X-ray detector enabled X-ray diffraction intensity mapping in the reciprocal lattice space at a rate of less than 10 s per frame. A series of X-ray diffraction images revealed the evolution of the strain, composition and height of InAs quantum dots during the growth process including InAs nanoisland formation, growth interruption and encapsulation with GaAs. Because the propagation of X-rays is not hindered even in gaseous atmosphere, this technique can be applied to vapor-phase epitaxy as well and thus is suitable for industrial applications.
Takeda, Masayasu
Transactions of the Materials Research Society of Japan, 32(1), p.199 - 202, 2007/03
no abstracts in English
Takano, Katsuyoshi; Inoue, Aichi; Yamamoto, Shunya; Miyashita, Atsumi; Yoshikawa, Masahito
Transactions of the Materials Research Society of Japan, 32(1), p.159 - 162, 2007/03
Ion irradiations with 
He
at 350 keV were performed for the tungsten tri-oxide (WO
) films. Gasochromic coloration of the irradiated films was observed by a measurement of optical transmittance with the expose of 1 % hydrogen. The extent of coloration level of the irradiated film with the fluence of 
ions/sm
is 7.5 times lager than that of non-irradiated film. W 4
photoemission spectra for the films were measured by X-ray photoelectron spectroscopy. From the fitting analysis for the spectra, the non-irradiated film has only W
. In the irradiated film with the fluence of ions/sm, it is estimated that 17 % and 4 % of the amount of W change into W
and W
, respectively. The improvement of the gasochromic coloration of the irradiated WO films relates to the increment of oxygen deficient tungstens induced by the irradiation.
RuO
(=La, Pr and Nd, =Mg, Co, Ni and Zn)Yoshii, Kenji; Ikeda, Naoshi*; Mori, Shigeo*; Yoneda, Yasuhiro; Mizumaki, Masaichiro*; Tanida, Hajime*; Kawamura, Naomi*
Transactions of the Materials Research Society of Japan, 32(1), p.51 - 54, 2007/03
Magnetic and dielectric properties of the ruthenium double perovskites RuO were studied ( = Co, Ni, Zn, Mg). The materials with the magnetic M
ions ( = Co and Ni) showed magnetic ordering and large dielectric constants (about 5000). On the other hand, for the non-magnetic M ions ( = Mg and Zn), magnetic ordering was not observed. In addition, their dielectric constants were found to be small (about 100-200). Together with the result of the dielectric response, the large dielectric constants for =Co and Ni may be related to a smooth response of polar regions. Investigations of the properties of RuO with =Pr and Nd are also being carried out, and their results are briefly discussed.
filmsInoue, Aichi; Yamamoto, Shunya; Nagata, Shinji*; Takano, Katsuyoshi; Yoshikawa, Masahito; Shikama, Tatsuo*
Transactions of the Materials Research Society of Japan, 32(1), p.107 - 110, 2007/03
We investigated the gasochromic coloration of amorphous tungsten oxide films having compositions between WO
and WO
. The films were deposited on SiO or glassy carbon substrates by the reactive radio frequency (r. f.) magnetron sputtering with varying oxygen partial pressure. The oxygen and hydrogen concentration of the tungsten oxide films were determined using the Rutherford Backscattering Spectrometry (RBS) and the Elastic Recoil Detection Analysis (ERDA), respectively. The optical transmission was examined for the films coated with palladium catalysis during the exposure of diluted hydrogen gas. Superior gasochromic properties were obtained for the films consisting of tungsten trioxide WO
. For the films with lower oxygen concentration than WO, the optical transmission hardly changed during the hydrogen exposure. A large concentration of hydrogen about 0.7 per a tungsten atom was found in the WO films. The hydrogen retention drastically decreased with a decrease of the oxygen concentration.
Owada, Kenji; Namikawa, Kazumichi; Mizuki, Junichiro; Shimomura, Susumu*; Nakao, Hironori*; Ito, Kazuki*; Matsushita, Mitsuyoshi*; Yoneda, Yasuhiro; Murakami, Yoichi*; Hirota, Kazuma*
Transactions of the Materials Research Society of Japan, 32(1), p.7 - 10, 2007/03
An X-ray speckle pattern well reflects a particle or domain alignment on the inside of materials. Detecting the alignment is important for understanding a function of the materials such as ferroelectric, piezoelectric materials, photonic crystals and so on. We have thus constructed the apparatus for coherent X-ray diffraction at BL22XU@SPring-8, high quality slits for obtaining the full coherent X-ray beam, high resolution X-ray CCD camera for obtaining the well-resolved speckle pattern, and so on. By using the devices, we have successfully observed the speckle pattern from CuAu, the ferroelectric material PZN-9%PT (91%Pb(Zn
Nb
)O-9%PbTiO) and Sr-doped BaTiO. The 2DFFT image gives us a spatial autocorrelation function which includes the information of the arrangement of the domains in the crystal within micrometers scale.
crystal by synchrotron X-ray topographyYoneda, Yasuhiro; Komura, Yoshiki*; Suzuki, Yoshio*; Morimura, Ryota*; Kojima, Akira*; Mizuki, Junichiro
Transactions of the Materials Research Society of Japan, 32(1), p.31 - 34, 2007/03
We performed X-ray diffraction topography on a BaTiO single crystal by high-coherent synchrotron X-rays. Since the domain configuration of the BaTiO crystal was unstable and fluctuated as temperature fluctuated, an excellent temperature control system is needed for the domain observation. We used a milli-Kelvin (mK) cell, which can control a BaTiO crystal within 
1mK. By combining the coherent X-ray and the mK-cell, one can detect the lattice strain very sensitively around the domain boundary. The lattice strain reduced as temperature increased, and disappeared at 100
C, which is much lower than the phase transition temperature of the BaTiO, and the BaTiO crystal still remained in the ferroelectric tetragonal phase. This behavior can be interpreted by the existence of the so-called "non-strain-free style domain", which is reported firstly by Takashige et al.
Yamamoto, Shunya; Takano, Katsuyoshi; Inoue, Aichi; Yoshikawa, Masahito
Transactions of the Materials Research Society of Japan, 32(1), p.171 - 174, 2007/03
The gasochromic materials have considerable promise as the optical gas sensors. Palladium oxide is known to exhibit optical absorbance changes due to the reduction reaction with hydrogen gas. However, the gasochromic performance of palladium oxide films is strongly influenced by preparation conditions, such as a heat-treatment temperature. We investigate the correlation between of oxidation temperature of Pd films and the gasochromic performance for hydrogen. Palladium oxide films are prepared by thermal oxidation of the Pd films at temperature ranging from 300 to 900C in air. The gasochromic performance of palladium oxide films coated with Pd catalyst was examined by optical transmission in 1% hydrogen with argon gas. The palladium oxide film, thermally oxidized at 600C in air, shows the good gasochromic performance. The results should lead to an optimization of preparation conditions to provide the gasochromic films used for the optical hydrogen sensors.
Nagata, Shinji*; Tsuchiya, Bun*; Takahiro, Katsumi*; Ozaki, Koichi*; Inoue, Aichi; Yamamoto, Shunya; To, Kentaro*; Shikama, Tatsuo*; Kawatsura, Kiyoshi*
no journal, ,
Effect of the ion implantation on the phase transformation was studied for Zr
Al
Ni
Cu
glassy and crystalline alloys, using Au, Pt and Cu ions with 500 keV up to a fluence of 8
10
m
. In the glassy ZrAlNiCu alloys, the formation of a meta-stable or an ichosahedral phase was promoted as the primary precipitates, by successive heat treatment after the ion implantation. Ion induced amorphization and the suppression of the thermal precipitation was found in the pre-crystallized alloy. The Au atoms were retained along to their projected ranges at room temperature and did not diffuse during the heat treatment at 760 K for 30 s. On the other hand, implanted Pt atoms were not detected in the implanted layer even at room temperature. Changes of the binding energy of the core level electron and valence band structure indicated the formation of Au-Cu alloys in the implanted region.
Takahiro, Katsumi*; Kawatsura, Kiyoshi*; Zhang, K.*; Rotter, F.*; Schwen, D.*; Ronning, C.*; Hofs
ss, H.*; Krauser, J.*; Nagata, Shinji*; Yamamoto, Shunya; et al.
no journal, ,
In order to study the allotropic effect on ripple formation on carbon surfaces induced by sputter erosion, three types of carbon materials, highly oriented pyrolytic graphite (HOPG), single crystalline diamond and tetrahedral amorphous carbon (ta-C) films, were irradiated with 5 keV Xe
at an incident angle of 30 degree. The irradiation fluence was 210
cm for all irradiations. No ripples were formed on diamond and ta-C surfaces, while ripples with a wavelength of 
100 nm occurred on HOPG. Electron energy loss spectroscopy revealed that the surfaces of all carbon materials became amorphous with similar densities upon irradiation. Therefore, the presented results clearly show that rippling depends on the nature of the underlying carbon materials. The mechanism for rippling of carbon materials will be discussed.
Narumi, Issei; Oba, Hirofumi; Sato, Katsuya; Sghaier, H.
no journal, ,
no abstracts in English
Yamaki, Tetsuya; Kawahito, Shimpei; Sawada, Shinichi; Asano, Masaharu; Suzuki, Akihiro*; Terai, Takayuki*; Maekawa, Yasunari
no journal, ,
no abstracts in English