Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Hattori, Takanori; Arima, Hiroshi; Sano, Asami; Utsumi, Wataru; Inoue, Toru*; Kagi, Hiroyuki*; Yagi, Takehiko*
no journal, ,
The PLANET is the new high-pressure neutron beamline now being constructed at the intense pulsed neutron source J-PARC. This beamline aims at revealing the effect of water on dynamics of the interior of the Earth and planets by using the neutron character that is sensitive to hydrogen. The most characteristic feature of this beamline is to posses the huge 6-axis press with the maximum load of 500 ton/axis, which can simultaneously generate high-pressure and high-temperature condition of 30 GPa and 2000 K. Coupled with the state-of-the-art techniques in neutron diffraction and radiography, the beamline offers the microscopic and macroscopic information of materials at high-PT condition. We stared designing at 2008 and already installed all the beamline components except those scheduled to be installed inside the experimental hutch. The huge press and detector banks have been constructed and are waiting to be installed. The installation will be finished in 2011, and the commissioning will starts at 2012.
Matsuoka, Takehiro*; Shimizu, Katsuya*; Fujihisa, Hiroshi*; Hirao, Naohisa*; Oishi, Yasuo*; Yoda, Yoshitaka*; Mitsui, Takaya; Masuda, Ryo; Machida, Akihiko; Aoki, Katsutoshi; et al.
no journal, ,
Europium-hydride EuH
exposed to high-pressure H conditions has been studied by X-ray diffraction and M
ssbauer spectroscopy measurements up to 50 GPa using synchrotron radiation. We report new structural and valence transitions, Pnma(x=2, divalent) 
P63/mmc(x=2, 7.2-8.7GPa) I4/m(x
2, 8.7-9.7 GPa) I4/mmm(x2, 9.7 GPa, trivalent). The phase of I4/mmm having trivalent character is a small distortion from cubic fcc structure which has been commonly observed for 
-phase of all other trivalent rare-earth metal hydrides. Our study clearly demonstrates the first observation of -phase of EuH and suggest that the material is no longer an irregular member of the rare earth metal hydrides RH systems.
Okada, Taku*; Yagi, Takehiko*; Aoki, Katsutoshi; Eremets, M.*; Trojan, I.*
no journal, ,
Ice is a major constituent component in icy planets and satellites. Ice is considered as a solid electrode with protons as a carrier and hence the first potential candidate as an inner core of them if they exhibit magnetic fields. The proton conductivity of ice has been measured for a pressure range from 2 to 60 GPa by AC impedance technique. The results showing a maximum around 10 GPa is presented and discussed on the basis of incommensurating phase appearing in the high pressure ice.
glass study by RMC simulation using X-ray and neutron diffraction dataYagafarov, O.; Kohara, Shinji*; Temleitner, L.*; Inamura, Yasuhiro; Katayama, Yoshinori
no journal, ,
Yagafarov, O.; Katayama, Yoshinori; Brazhkin, V. V.*; Lyapin, A. G.*; Saito, Hiroyuki
no journal, ,
Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori; Aoki, Katsutoshi
no journal, ,
no abstracts in English
at high pressures and high temperaturesEndo, Naruki; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori; Aoki, Katsutoshi
no journal, ,
no abstracts in English
Tateiwa, Naoyuki; Haga, Yoshinori; Matsuda, Tatsuma; Yamamoto, Etsuji; Onuki, Yoshichika; Fisk, Z.
no journal, ,
We have studied the high pressure physical properties of uranium compounds. There is no tendency in the pressure dependences of the magnetic transition temperatures in the uranium compounds. The applying pressure induces a first order phase transition and the ground state is switched accordingly. In this talk, we firstly introduce our high pressure apparatuses such as the diamond anvil cell or other pressure cells now being investigated. Then, we would like to show some experimental data on uranium antiferromagnetic compounds as well as a semiconducting uranium chalcogenide.
Tateiwa, Naoyuki; Haga, Yoshinori; Onuki, Yoshichika; Fisk, Z.
no journal, ,
Several types of the high pressure cell have been proposed to for magnetic measuremets in the SQUID magnetometer so far. Most pressure cells are of the piston-cylinder type whose maximum pressure is at most 1.5 GPa. The diamond anvil cell can generate the high pressure up to 15 GPa. But the volume of the sample space is too small to be applied to antiferromagnetic compounds with small magnetization. We propose a miniature ceramic anvil cell for magnetic measurements under high pressure. The cell can be used for a material with smaller magnetization since the back ground magnetization is far smaller than that in the indenter cell. The maximum pressure is about 7.6 GPa.
and formatiom of monodeuteride LaDMachida, Akihiko; Honda, Mitsunori*; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Arima, Hiroshi*; Komatsu, Kazuki*; Oshita, Hidetoshi*; et al.
no journal, ,
no abstracts in English
Honda, Mitsunori*; Machida, Akihiko; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Arima, Hiroshi*; Komatsu, Kazuki*; Oshita, Hidetoshi*; et al.
no journal, ,
no abstracts in English
Osakabe, Toyotaka; Inatani, Koichi*; Kuwahara, Keitaro*; Kitazawa, Hideaki*
no journal, ,
no abstracts in English
Abe, Jun; Komatsu, Kazuki*; Arima, Hiroshi*; Hattori, Takanori; Sano, Asami; Arakawa, Masashi*; Kagi, Hiroyuki; Okuchi, Takuo*; Utsumi, Wataru
no journal, ,
We have performed high-pressure neutron diffraction experiments using newly designed cubic-anvil high-pressure cell. Incident and diffracted neutron beams travel through high-pressure device, which causes attenuation of neutron. We have studied the method of attenuation correction and analyzed crystal structure using corrected neutron diffraction pattern. The total attenuation of the diffracted neutron beam is calculated by ray tracing. Neutron diffracted pattern of AlO
in cubic-anvil high-pressure device have been measured and carried out the attenuation correction. Crystal structure was analyzed by the Rietveld method. Atomic coordinates and displacement parameters of AlO in cubic-anvil high-pressure device agreed with those obtained by using sample holder.
Sano, Asami; Yagi, Takehiko*; Hattori, Takanori; Arima, Hiroshi*; Abe, Jun; Komatsu, Kazuki*
no journal, ,
CrOOH and CrOOD (gyanite) are known to have a short O...O distance and to display a strong D/H isotope effect on their geometry. In this study, compression experiment on CrOOH and CrOOD was conducted up to 31 GPa. The deuteration of CrOOH resulted in a change in compressibility of the b-axis. The compressibility of the a and c axes of CrOOD did not differ significantly from those of CrOOH. However, the b-axis of CrOOD became more compressible compared to that of CrOOH at pressures below 4 GPa. Above 4 GPa, the b-axis became less compressible as compared to its behavior at lower pressures, which suggests anisotropic stiffening. The stiffening behaviors that were observed in the present study can be attributed to the symmetrization of the hydrogen bonds in oxyhydroxides, as was previously found in 
-AlOOH.
Katayama, Yoshinori; Saito, Hiroyuki; Aoki, Katsutoshi
no journal, ,
Hydrogen reacts with many metals and form metal hydrides. In transition metal hydrides, hydrogen atoms usually occupy interstitial sites and the crystalline lattice expands. To study effect of hydrogen to the structure of liquid metals, we have studied a liquid iron hydrogen alloy under high pressure and found that the Fe-Fe distance slightly increased upon hydrogenation. In this study, we have measured X-ray diffraction of liquid nickel, cobalt and manganese hydrogen alloys for comparison. Measurements were carried out using a cubic-type multi-anvil press on BL14B1 at SPring-8. Structure factor, S(Q), of MH at about 4 GPa was obtained (M=Ni, Co, Mn). Structure factor of each pure metal was also measured at about 3.5 GPa. In all metals, the M-M distance slightly increased upon hydrogenation and the structural changes were not significant.
Watanuki, Tetsu; Kawana, Daichi*; Machida, Akihiko; Tsai, A. P.*; Kashimoto, Shiro*; Tanaka, Yukinori*; Ishimasa, Tsutomu*
no journal, ,
no abstracts in English