Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Saito, Hiroyuki; Okajima, Yuka*; Yoneda, Yasuhiro; Machida, Akihiko; Katayama, Yoshinori; Aoki, Katsutoshi
no journal, ,
no abstracts in English
Saito, Hiroyuki; Abe, Jun; Katayama, Yoshinori
no journal, ,
no abstracts in English
Sano, Asami; Hattori, Takanori; Utsumi, Wataru; Komatsu, Kazuki*; Kagi, Hiroyuki*; Nagai, Takaya*
no journal, ,
-AlOOH, distorted rutile type oxyhydroxide, is an important hydrous mineral in the deep earth that has the ability to transport hydrogen into the lower mantle. Theoretical studies have pointed out that hydrogen would locate at the center between two oxygen atoms at high pressure, which is so called symmetrization of the hydrogen bond. To investigate the pressure response of strong hydrogen bond -AlOOH, we conduct neutron diffraction experiment at SNAP in SNS. Neutron diffraction patterns of -AlOOH was measured on SNAP to 7 GPa. The intensity of the peak that is only observed in the space group P2
nm become weak at high pressure suggesting the transition to H-disordered or symmetric hydrogen bond model with Pnnm.
Katayama, Yoshinori; Yagafarov, O.; Hattori, Takanori; Suzuya, Kentaro; Inamura, Yasuhiro; Chiba, Ayano*; Otomo, Toshiya*; Temleitner, L.*; Kohara, Shinji*
no journal, ,
The purpose of our project is structural analysis of liquid water and other structurally disordered materials under high pressure using a high-pressure neutron beamline which is under construction in J-PARC/MLF. In this presentation, we will review recent studies toward the neutron experiments, such as synchrotron radiation X-ray diffraction studies on liquid water under high-pressure and high-temperature conditions, and Reverse Monte Carlo modeling of permanently densified silica glass using both X-ray and neutron data.
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 liquid iron hydrogen alloys before. In this study, we have measured X-ray diffraction of liquid nickel hydrogen alloy for comparison. Measurements were carried out at 4 GPa using a cubic-type multi-anvil press on BL14B1 at SPring-8. The decrease of melting temperature was confirmed. The position of the first peak in the pair distribution function for NiH
indicates that nickel-nickel inter atomic distance elongates by hydrogenation.
Machida, Akihiko; Watanuki, Tetsu; Kawana, Daichi*; Aoki, Katsutoshi
no journal, ,
We have investigated the temperature effect on the pressure-induced phase separation in LaH by synchrotron radiation X-ray diffraction experiments at low temperature. The phase separation was observed at 13.5 GPa which is slightly higher than that at room temperature. This is because the mobility of the interstitial hydrogen atoms was suppressed at low temperature. The pressure-induced phase separation will be discussed on the basis of the further analysis of the X-ray data.
Arima, Hiroshi; Komatsu, Kazuki*; Kagi, Hiroyuki*; Abe, Jun; Sano, Asami; Hattori, Takanori; Utsumi, Wataru
no journal, ,
There are principal experimental obstacles for neutron diffraction measurements under high-pressure conditions. One is very weak signal obtained from the tiny sample of only a few cubic millimeters volume. Therefore, it is necessary to focus the neutron beam spatially at a small spot below a few square millimeters so as to increase the flux at the sample position and to reduce background noise. In this study, a supermirror guide for high-pressure diffraction study is developed. The test results show that the guide can lead to a flux gain of about 1.4 at sample position for the neutron wavelength above 0.7 
.
Hattori, Takanori; Arima, Hiroshi; Sano, Asami; Abe, Jun; Utsumi, Wataru; Kagi, Hiroyuki*; Yagi, Takehiko*
no journal, ,
PLANET is the high-pressure neutron diffractometer, which is now being constructed at MLF in J-PARC. This diffractometer aims to reveal the effect of water on the materials dynamics in the earth, with the help of the neutron character that is sensitive to hydrogen. The most characteristic feature of the diffractometer is to install the new type of the press, ATUMIME. The press has six independently controlled compression axes with the maximum concentric load of 3000 ton, which can realize simultaneous generation of the high-pressure and temperature of about 30 GPa and 2000 K. Coupling this with the techniques of neutron diffraction, neutron imaging, we can reveal the high-pressure states of the crystals, liquid and amorphous solids. This paper overviews the diffractometer and its construction state.
Abe, Jun; Hattori, Takanori; Arima, Hiroshi; Sano, Asami; Fukazawa, Hiroshi; Utsumi, Wataru; Komatsu, Kazuki*; Arakawa, Masashi*; Iizuka, Riko*; Kagi, Hiroyuki*; et al.
no journal, ,
In order to confirm the feasibility of high-pressure neutron diffraction at TAKUMI, we have performed a number of R&Ds using a various high-pressure devices. Optimization of materials such as anvil and pressure medium and developments of collimators have made possible reduction of background and contamination noise. Incident and diffracted neutron beams travel through high-pressure device, which causes attenuation of neutron. We investigated the method of attenuation correction.
Honda, Mitsunori; Hattori, Takanori; Sano, Asami; Machida, Akihiko; Katayama, Yoshinori; Arima, Hiroshi; Komatsu, Kazuki*; Oshita, Hidetoshi*; Otomo, Toshiya*
no journal, ,
no abstracts in English
P
under 10 GPaOsakabe, Toyotaka; Yamauchi, Hiroki; Kuwahara, Keitaro*; Iwasa, Kazuaki*; Aoki, Yuji*; Sato, Hideyuki*; Kogi, Masafumi*
no journal, ,
no abstracts in English
Watanuki, Tetsu; Kawana, Daichi*; Machida, Akihiko; Tsai, A. P.*
no journal, ,
no abstracts in English