X-ray diffraction measurement of the hydrogenation and dehydrogenation of aluminum and characterization of the recovered AlH

Saito, Hiroyuki; Sakurai, Yoko; Machida, Akihiko; Katayama, Yoshinori; Aoki, Katsutoshi

Journal of Physics; Conference Series, 215, p.012127_1 - 012127_4, 2010/03

https://doi.org/10.1088/1742-6596/215/1/012127

Appropriate pressure-transmitting media for cryogenic experiment in the diamond anvil cell up to 10 GPa

Tateiwa, Naoyuki; Haga, Yoshinori

Journal of Physics; Conference Series, 215, p.012178_1 - 012178_7, 2010/03

https://doi.org/10.1088/1742-6596/215/1/012178

We evaluated the qualities of pressure-transmitting media by the ruby fluorescence method at room temperature, 77 and 4.2 K in the diamond anvil cell (DAC) up to 10 GPa in order to find appropriate media for the low temperature experiment. Investigations were done on fourteen kinds of media: a 1:1 mixture by volume of Fluorinert FC-70 and FC-77, Daphne 7373 and 7474, NaCl, silicon oil (polydimethylsiloxane), vaselin, 2-propanol, glycerin, a 1:1 mixture by volume of -pentane and isopentane, a 4:1 mixture by volume of methanol and ethanol, petroleum ether, nitrogen, argon and helium. We discuss the non-hydrostatic effects of the pressure in the media from the broadening effect of the ruby fluorescence line. The media are classified into three groups (I, II and III) from the values of FWHM at 5 GPa and 77 K: a relative increase of the width of the ruby line to the ambient value.

Large-volume static compression using nano-polycrystalline diamond for opposed anvils in compact cells

Okuchi, Takuo*; Sasaki, Shigeo*; Osakabe, Toyotaka; Ono, Yoshiki*; Odake, Shoko*; Kagi, Hiroyuki*

Journal of Physics; Conference Series, 215, p.012188_1 - 012188_9, 2010/03

https://doi.org/10.1088/1742-6596/215/1/012188

We prepared super-hard nano-polycrystalline diamond (NPD) anvils for large-volume compression for intrinsically low-sensitivity methods of measurement, such as neutron scattering and NMR. These anvils are harder, larger and stronger than single crystal diamond anvils, so that they could play an ideal role to accept the larger forces. We tested supported and unsupported anvil geometries separately by using two types of compact high-pressure cells and could generate the pressure of 14 GPa for the sample volume of 0.1 mm or more. The test results demonstrate a large future potential of NPD anvils for large-volume compression.

Powder X-ray diffraction study of Ne up to 240 GPa

Takemura, Kenichi*; Watanuki, Tetsu; Owada, Kenji; Machida, Akihiko; Omura, Ayako*; Aoki, Katsutoshi

Journal of Physics; Conference Series, 215, p.012017_1 - 012017_4, 2010/03

https://doi.org/10.1088/1742-6596/215/1/012017

Powder X-ray diffraction experiments have been done on Ne up to 237 GPa at room temperature. Ne remains in the fcc phase up to the highest pressure. In order to observe the weak 200 reflection at ultrahigh pressure we have used the tube-cross slit at the exit side of X-rays, which effectively reduced the scattered X-rays by the diamond anvil. The lattice parameters obtained from the 111 and 200 reflections significantly differ each other, implying the existence of sizable uniaxial stress in Ne at ultrahigh pressure.

Designing PLANET; Neutron beamline for high-pressure material science at J-PARC

Arima, Hiroshi*; Hattori, Takanori; Komatsu, Kazuki*; Abe, Jun; Utsumi, Wataru; Kagi, Hiroyuki*; Suzuki, Akio*; Suzuya, Kentaro; Kamiyama, Takashi*; Arai, Masatoshi; et al.

Journal of Physics; Conference Series, 215(1), p.012025_1 - 012025_6, 2010/03

https://doi.org/10.1088/1742-6596/215/1/012025

The powder diffractometer dedicated to high-pressure experiments (PLANET) is now being constructed on BL11 at the spallation neutron source of J-PARC. PLANET aims to study structures of hydrogen-bearing materials including dense hydrous minerals of the Earth's deep interior, magmas and light element liquids. The instrument will realize diffraction and radiography experiments for powder and liquid/glass samples at high pressures up to 20 GPa and 2000 K. It covers spacing from 0.2 to 4.1 at 90 bank within the first frame. The design and performance of PLANET have been evaluated using Monte Carlo simulations.

Strategy of high pressure research with pulsed neutron at J-PARC

Utsumi, Wataru; Kagi, Hiroyuki*; Hattori, Takanori; Arima, Hiroshi; Komatsu, Kazuki*; Abe, Jun; Nagai, Takaya*; Okuchi, Takuo*; Harjo, S.; Aizawa, Kazuya; et al.

no journal, , 

J-PARC is a new high-intensity proton accelerator research facility in Japan. It has a spallation neutron source that will produce the world highest intensity pulsed neutron. It is expected that high pressure material science and the investigation of the Earth's interior will greatly improve at J-PARC. A Paris-Edinburgh cell and a cubic anvil high pressure apparatus have been brought to an Engineering Materials Diffractometer(BL19) to conduct the first high pressure experiment. As the next stage, we are planning to construct a dedicated high pressure beamline that will open in 2011.

Pressure induced phase separation of rare-earth metal dihydrides

Machida, Akihiko; Watanuki, Tetsu; Kawana, Daichi; Aoki, Katsutoshi

no journal, , 

no abstracts in English

Successive phase transitions and valence change of the Yb ion in the Cd-Yb crystalline approximant to a quasicrystal

Watanuki, Tetsu; Kawana, Daichi; Machida, Akihiko; Tsai, A. P.*

no journal, , 

A single crystal X-ray diffraction study of the Cd-Yb crystalline approximant was performed under pressure up to 33 GPa at SPring-8. The bcc phase at ambient pressure transformed to a 3-fold ordered phase at about 12 GPa, and to 4-fold one at about 20 GPa. These phases are different from those found at the previous study. These Sequential transitions would be induced by continuous decrease of the ionic radius of the Yb ion.