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by hydrogenation of pure aluminum at high pressures and temperaturesSaito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori; Aoki, Katsutoshi
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no abstracts in English
Machida, Akihiko; Watanuki, Tetsu; Kawana, Daichi; Aoki, Katsutoshi
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We have investigated the structural properties of rare-earth metal hydrides by using synchrotron radiation X-ray diffraction experiments under high pressure. Rare-earth metal di-hydrides generally exhibit the fcc metal lattice, which contains hydrogen atoms in only tetrahedral interstitial sites. It is expected that the hydrogen atoms transfer to another interstitial site by compression of metal lattice. We found the pressure-induced disproportionation of yttrium di-hydride previously. In order to demonstrate that this reaction occurs for other hydrides, we have performed synchrotron radiation X-ray diffraction experiments for lanthanum di-hydride under high pressure and have found the appearance of second phase.
Utsumi, Wataru; Abe, Jun; Hattori, Takanori; Fukazawa, Hiroshi; Yamauchi, Hiroki; Igawa, Naoki; Kagi, Hiroyuki; Arima, Hiroshi*; Arakawa, Masashi; Komatsu, Kazuki*; et al.
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no abstracts in English
Katayama, Yoshinori; Saito, Hiroyuki; Yomogida, Yoshiki; Aoki, Katsutoshi
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Hydrogen reacts with many metals and form hydrides. Although iron is not hydrogenated at ambient conditions, it forms hydride under high pressure. The melting temperature of iron hydride is lower than that of pure iron by 500
C at 5 GPa. To investigate effect of hydrogen to the structure of liquid, we have performed in-situ X-ray diffraction experiment on iron hydride produced under high hydrogen pressure. The measurements were carried out on BL14B1 at SPring-8. LiAlH4 was used as a hydrogen source. By heating at 5 GPa, the hydrogen source decomposed and released hydrogen. X-ray measurements confirmed hydrogenation of iron and the decrease of the melting temperature. We have also succeeded in a measurement of pure iron under high-pressure and high-temperature condition. The effect of hydrogen on the structure of liquid iron will be discussed.
Hattori, Takanori; Katayama, Yoshinori; Machida, Akihiko; Otomo, Toshiya*; Suzuya, Kentaro
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The neutron experiments at J-PARC, which was constructed recently, offer new information on materials, such as atomic position of light elements and the dynamic structures, so many scientists are waiting for that use. Still now we could not get the beamline specially dedicated for high-pressure study, we are waiting the chance to do neutron experiments at another beamlines. The intense total scattering beamline NOVA, which is constructed under the program HYDROSTAR based on the NEDO's fund, is one of the powerful beamlines for studying disordered materials under pressure. So, we also attend the program and are planning to do the neutron experiments at NOVA using a compact Paris-Edinburgh cell. We introduce the characteristics of NOVA and the current state of our high-pressure experiments.
Abe, Jun; Harjo, S.; Moriai, Atsushi; Ito, Takayoshi; Aizawa, Kazuya; Arai, Masatoshi; Arima, Hiroshi; Kagi, Hiroyuki; Hattori, Takanori; Utsumi, Wataru
no journal, ,
The Engineering Materials Diffractometer TAKUMI designed to solve many problems in materials science and engineering including investigations of stresses and crystallographic structures within engineering components was developed at J-PARC. In addition, TAKUMI is suitable for high pressure experiments. High pressure devices (Paris-Edinburgh press and palm cubic anvil press) were developed for in situ neutron powder diffraction experiments under high pressures. In this presentation, we introduce outline of TAKUMI and High pressure devices.
Tateiwa, Naoyuki; Haga, Yoshinori; Matsuda, Tatsuma; Ikeda, Shugo*; Onuki, Yoshichika
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We have studied the high pressure physical properties of uranium compounds. In this presentation, I will show our experimental data on uranium antiferromagnet U
Zn
. The pressure dependence of the antiferromagnetic transition temperature was investigated by the electrical resistivity measurement up to 8.7 GPa using a diamond anvil cell. I will make some discussions on unusual high pressure response of the electronic state in the compound.
Kawana, Daichi; Watanuki, Tetsu; Machida, Akihiko; Shobu, Takahisa; Aoki, Katsutoshi; Tsai, A. P.*
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no abstracts in English
Osakabe, Toyotaka
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We developed a hybrid-anvil device, which is composed of a WC anvil and a sapphire anvil for magnetic neutron diffraction studies under 10 GPa. To prevent the crack of the sapphire anvil above about 7 GPa, we tried the three types of the anvils instead of the sapphire anvil: (1) sapphire anvil with a diamond cap, (2) sapphire anvil supported by MP35N alloy, and (3) SiC anvil supported by MP35N alloy. The test result shows that the (3) anvil can generate the pressure of 10 GPa at the load of about 3.8 tons with no failure.
Watanuki, Tetsu; Machida, Akihiko; Kawana, Daichi; Tsai, A. P.*
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no abstracts in English
using infrared reflection spectroscopySakurai, Yoko; Machida, Akihiko; Aoki, Katsutoshi
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no abstracts in English