Yamashita, Keishiro*; Komatsu, Kazuki*; Ohara, Takashi; Munakata, Koji*; Irifune, Tetsuo*; Shimmei, Toru*; Sugiyama, Kazumasa*; Kawamata, Toru*; Kagi, Hiroyuki*
High Pressure Research, 42(1), p.121 - 135, 2022/03
Hattori, Takanori; Sano, Asami; Machida, Shinichi*; Ouchi, Keiichi*; Kira, Hiroshi*; Abe, Jun*; Funakoshi, Kenichi*
High Pressure Research, 40(3), p.325 - 338, 2020/09
To understand the practical effects of pressure-transmitting media (PTM) on neutron diffraction using Paris-Edinburgh presses, diffraction patterns of MgO were collected to approximately 20 GPa using PTMs of Pb, AgCl, 4:1 methano-ethanol (ME) mixture with and without heating, N, and Ar. Hydrostaticity in the sample chamber estimated from the MgO 220 peak width improves in the order of Pb, AgCl, Ar, ME mixture, N, and the heated ME mixture. Unlike previous results using a diamond anvil cell, the unheated ME mixture is superior to Ar even after freezing, probably due to the cup on the anvil face. Considering these results and the sizable coherent scattering of Ne, which would show good hydrostaticity, we conclude that the ME mixture (preferably the heated one) is the best PTM in neutron experiments up to 20 GPa, while Ar can be substituted when a sample is reactive to alcohols.
Komatsu, Kazuki*; Klotz, S.*; Nakano, Satoshi*; Machida, Shinichi*; Hattori, Takanori; Sano, Asami; Yamashita, Keishiro*; Irifune, Tetsuo*
High Pressure Research, 40(1), p.184 - 193, 2020/02
A new high pressure cells for neutron diffraction experiments using nano-polycrystalline anvil is presented. The cell design, off-line pressure generation tests and a gas-loading procedure for this cell are described. The performance is illustrated by powder neutron diffraction patterns of ice VII to 82 GPa. We also demonstrate the feasibility of single crystal neutron diffraction experiments of FeO at ambient conditions using this cell and discuss the current limitation and future developments.
Hattori, Takanori; Sano, Asami; Machida, Shinichi*; Abe, Jun*; Funakoshi, Kenichi*; Arima, Hiroshi*; Okazaki, Nobuo*
High Pressure Research, 39(3), p.417 - 425, 2019/06
We have developed a technique for neutron diffraction experiments at pressures up to 40 GPa using a Paris-Edinburgh press at the PLANET beamline in J-PARC. To increase the maximum accessible pressure, the diameter of the dimple for sample chamber at the top of the sintered diamond anvils is sequentially reduced from 4.0 mm to 1.0 mm. As a result, the maximum pressure increased and finally reached 40 GPa. By combining this technique with the beam optics which defines the gauge volume, diffraction patterns sufficient for full-structure refinements are obtainable at such pressures.
Yagafarov, O.; Katayama, Yoshinori; Brazhkin, V. V.*; Lyapin, A. G.*; Saito, Hiroyuki
High Pressure Research, 33(1), p.191 - 195, 2013/01
Saito, Hiroyuki; Abe, Jun
High Pressure Research, 31(3), p.407 - 412, 2011/09
Tateiwa, Naoyuki; Haga, Yoshinori; Matsuda, Tatsuma; Yamamoto, Etsuji; Ikeda, Shugo; Onuki, Yoshichika*
High Pressure Research, 26(4), p.471 - 474, 2006/12
We investigated non-centrosymmetric compounds CePtSi and UIr by the ac heat capacity measurement under pressures. The pressure phase diagrams are determined. In CePtSi, the Nel temperature = 2.2 K decreases with increasing pressure and becomes zero at the critical pressure 0.6 GPa. On the other hand, the superconducting phase exists in a wider pressure region from ambient pressure to about 1.5 GPa. The phase diagram of CePtSi is thus very unique. In the ferromagnetic compound UIr where successive ferromagnetic transitions appear under pressure, the heat capacity shows an anomaly at the Curie temperature and this anomaly shifts to lower temperatures with increasing pressure. The present pressure dependence of was consistent with the previous works by the resistivity and magnetization measurements.
Matsuoka, Takehiro*; Kitayama, Takayasu*; Shimizu, Katsuya*; Nakamoto, Yuki*; Kagayama, Tomoko*; Aoki, Katsutoshi; Oishi, Yasuo*; Takemura, Kenichi*
High Pressure Research, 26(4), p.391 - 394, 2006/12
The electrical and structural properties of yttrium hydride YHx was studied by the in-situ measurements of the electrical resistance and X-ray diffraction up to 86 GPa. The electrical resistivity increased with applying pressure up to 10 GPa and showed a maximum which accompanied with the structural transition of metal lattice from hcp to fcc structure. In fcc phase the resistivity decreased significantly, however the value still remained larger by 4 orders of magnitude that that of pure yttrium metal. We could not confirm the insulator to metal transition up to 23 GPa. The resistivity showed another maximum in the large pressure region 40 60 GPa without the structural phase transition of metal lattice.
Okube, Maki*; Yoshiasa, Akira*; Otaka, Osamu*; Katayama, Yoshinori
High Pressure Research, 23(3), p.247 - 251, 2003/09
In order to examine the pressure effect on anharmonic thermal vibrations of Pt, Extended X-ray Absorption Fine Structure (EXAFS) spectra near Pt K-edge and L-edge were measured in the temperature range from 300 to 800K under pressures up to 6vGPa, using large volume high-pressure devices and synchrotron radiation. We have investigated the anharmonic interatomic potentials by a cumulant expansion method. The values of EXAFS Debye-Waller factors, 2 and 3, become smaller with increase of pressure. The anharmonic effective pair potential was evaluated and the potential coefficient a at 0.1MPa and 6GPa are 4.8 and 5.0eV/, respectively. The anharmonic potential parameter decreases with increasing pressure.
Otaka, Osamu*; Fukui, Hiroyuki*; Funakoshi, Kenichi*; Utsumi, Wataru; Irifune, Tetsuo*; Kikegawa, Takumi*
High Pressure Research, 22(1), p.221 - 226, 2002/01
no abstracts in English
Urakawa, Satoru*; Hasegawa, Masayuki*; Yamakawa, Junji*; Funakoshi, Kenichi*; Utsumi, Wataru
High Pressure Research, 22(2), p.491 - 494, 2002/01
no abstracts in English
Urakawa, Satoru*; Igawa, Naoki; Umesaki, Norimasa*; Igarashi, Kazuo*; Shimomura, Osamu*; Ono, Hideo
High Pressure Research, 14(4-6), p.375 - 382, 1996/12
no abstracts in English