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Aoki, Katsutoshi*; Machida, Akihiko*; Saito, Hiroyuki*; Hattori, Takanori
Koatsuryoku No Kagaku To Gijutsu, 35(1), p.4 - 11, 2025/03
Iron reacts with hydrogen to form solid solutions with body-centered cubic, face-centered cubic, hexagonal close packed, and double hexagonal close packed structures at high temperatures and high pressures. Neutron diffraction is the most powerful tool for determining the occupation sites and occupancies of hydrogen atoms dissolved in a metal lattice. Structural parameters, including hydrogen occupation sites and occupancies, are refined via Rietveld analysis for neutron diffraction data. We present our expertise in Rietveld refinement of iron hydrides accumulated over 10 years.
S
under pressureKosaka, Yusuke*; Oishi, Kazuki*; Hattori, Takanori
Koatsuryoku No Kagaku To Gijutsu, 34(3), p.121 - 126, 2024/09
Transition-metal intercalated dichalcogenides have attracted attention due to the observation of chiral helimagnetism (CHM) and chiral soliton lattice in CrNbS. It forms a chiral monoaxial crystal structure with a space group P622. To examine the pressure effect on the CHM period of CrNbS, we performed small-angle neutron scattering experiments with a piston-cylinder pressure cell up to 1.2 GPa. We observed a decrease in the magnetic transition temperature with increasing pressure. Moreover, the CHM period decreased with increasing pressure. Compared to the decrease of the lattice constant, that of the CHM period is much larger. This indicates that applying pressure weakens the amplitude of Dzyaloshinskii-Moriya interaction.
Machida, Shinichi*; Hattori, Takanori; Nakano, Satoshi*; Sano, Asami; Funakoshi, Kenichi*; Abe, Jun*
Koatsuryoku No Kagaku To Gijutsu, 34(3), p.134 - 142, 2024/09
A diamond anvil cell (DAC) for high-pressure neutron diffraction experiments has been developed at the PLANET beamline, Materials and Life Science Experimental Facility, in J-PARC. The conically supported diamond anvils were used for high-pressure generation. We succeeded in obtaining the neutron data for D
O ice up to 69.4 GPa. In addition, the gasket materials suitable for the neutron diffraction measurements were investigated. 11 kinds of alloys were tested and SUS304, Inconel718 and M2052 (73Mn-20Cu-5Ni-2Fe, at%) alloys showed excellent performance. Especially, M2052 null-matrix alloy has proven to be useful for neutron diffraction experiments where the beam inevitably hits the gasket. We then obtained refinable neutron diffraction profiles in Rietveld analysis from DO ice at least up to 43.3 GPa.
Sano, Asami; Ito, Shoichi*; Suzumura, Akimasa*; Ueno, Yuichiro*; Yagi, Hikaru*; Inoue, Toru*; Kawazoe, Takaaki*
Koatsuryoku No Kagaku To Gijutsu, 30(2), p.85 - 94, 2020/10
Minerals and rocks exhibit various isotope compositions depending on their origins and histories. In interpreting their isotopic variations, the equilibrium isotope fractionation factor is a key because it depends on the environment parameters such as temperature. Recent studies have shown that the effect of pressure on the isotope fractionation, which was considered negligible compared to temperature, is significant under the conditions of the Earth's interior. In this article we review recent advances in experimental studies to determine the isotope fractionation of iron and hydrogen at high pressure over several GPa, discussing their issues and future perspectives.
Hattori, Takanori; Sano, Asami; Arima, Hiroshi*; Funakoshi, Kenichi*; Abe, Jun*; Machida, Shinichi*; Okazaki, Nobuo*; Ouchi, Keiichi*; Inamura, Yasuhiro
Koatsuryoku No Kagaku To Gijutsu, 26(2), p.89 - 98, 2016/06
PLANET is a high-pressure neutron beamline constructed at pulsed-neutron source in Materials and Life Science Facility (MLF) in J-PARC. The six-axis multi-anvil press designed for time of flight (TOF) neutron diffraction experiments enables routine data collection at high pressures and high temperatures up to 10 GPa and 2000 K, respectively. To obtain clean data, the beamline is equipped with the incident slits and receiving collimators that eliminate parasitic scattering from the high-pressure cell. The high performance of the diffractometer for the resolution (
0.6%) and the accessible d-spacing range (0.2 - 8.4 
) together with low-parasitic scattering characteristics enables precise structure determination of crystals and liquids under high pressure and temperature conditions.
Tateiwa, Naoyuki
Koatsuryoku No Kagaku To Gijutsu, 25(4), p.274 - 282, 2016/01
I will review miniature ceramic anvil cell mCAC for magnetic measurements under high pressure. Recently, the SQUID magnetometer has been used by researchers. Several types of high pressure cell have been developed for the magnetometer. In this paper, I will introduce our miniature ceramic anvil cell mCAC in details. Precise measurements can be possible with the mCAC since the background magnetization is smaller than those of other types of the cell. Finally, experimental data on the rare earth compound YbCuSi will be shown. We detect pressure-induced ferromagnetic state in the compound above 10 GPa.
Osakabe, Toyotaka; Kato, Yoshihiro*; Honmoto, Satoru*; Kuwahara, Keitaro*
Koatsuryoku No Kagaku To Gijutsu, 25(1), p.57 - 63, 2015/03
In this article, we describe an unique technique for electrical insulation of metallic gasket to perform simultaneous measurements of electrical resistivity and neutron diffraction under high pressure. The anodic oxide coating was adopted as the insulation layer of the aluminum (JIS A2017) gasket used in the hybrid-anvil device for neutron diffraction. In the feasibility tests of the coated gaskets, maximum pressure of about 6 GPa was generated without electrical breakdown of the coating or disconnection of Au leads.
Owada, Kenji
Koatsuryoku No Kagaku To Gijutsu, 23(3), p.245 - 251, 2013/08
Application of coherent X-ray will be one of the main streams in the next generation synchrotron science. Many kinds of the methodologies have been established by using 3rd-generation synchrotron light sources. In this article, the author focuses on a so-called X-ray photon correlation spectroscopy (XPCS), and shows the recent advances in the application of XPCS to relaxor ferroelectrics.
Machida, Akihiko; Watanuki, Tetsu; Aoki, Katsutoshi
Koatsuryoku No Kagaku To Gijutsu, 21(3), p.168 - 175, 2011/10
This article reports the recent studies of the pressure-induced phase separation of rare-earth metal dihydrides. Synchrotron radiation X-ray diffraction patterns of LaH
shows that additional Bragg reflections appeared just outside of the original ones around 11 GPa, indicating the formation of the small fcc metal lattice. The coexistence state of two fcc metal lattices thus observed is interpreted in terms of phase separation from the dihydride toward lower and higher concentration phases. The formation of insulating LaH
(
) is confirmed by infrared spectroscopy, which shows decrease in reflection intensity. These results indicate that the interstitial hydrogen atoms transfer form T-sites and the domains of solid solution and higher concentration hydride are formed. Pressure-induced phase separation of metal hydrides would develop a new research field, that is, the dynamics of hydrogen transfer in a metal lattice.
conditions & electrical transport and structural properties of FeH
Matsuoka, Takehiro*; Hirao, Naohisa*; Oishi, Yasuo*; Shimizu, Katsuya*; Machida, Akihiko; Aoki, Katsutoshi
Koatsuryoku No Kagaku To Gijutsu, 21(3), p.190 - 196, 2011/09
We present the newly developed electrical resistance measurement technique for metal hydrides compressed in high-pressure H and the first successful 
simultaneous measurements of electrical resistance and X-ray diffraction of FeH at high pressures and low temperatures. The electrical resistivity 
showed a sharp increase with the formation of iron-hydride FeH (
) at 3.5 GPa. The 
'-phase of FeH was found to be metallic up to 25.5 GPa. The vs. 
curves up to 16.5 GPa approximately follow Fermi-liquid law below 25 K. However, 
was found to be better fitting at 25.5 GPa. This change can be related to the previously reported ferromagnetism collapse at corresponding pressures.
Kume, Tetsuji*; Machida, Akihiko; Aoki, Katsutoshi; Sasaki, Shigeo*; Shimizu, Hiroyasu*
Koatsuryoku No Kagaku To Gijutsu, 21(3), p.184 - 189, 2011/09
Raman and visible absorption spectra of rare earth trihydrides have been measured at high pressures, in order to investigate the structural and electronic phase transitions. The successive phase transitions of hcp-intermediatefcc phase were confirmed by Raman measurements. From the visible absorption experiments, the band gap energy was estimated. The gap closure was found to occur on the transition from the intermediate to the fcc phase.
for practical hydrogen storage materialSaito, Hiroyuki
Koatsuryoku No Kagaku To Gijutsu, 20(2), p.166 - 174, 2010/05
Aluminum tri-hydride (AlH) is promising as a hydrogen storage material. Hydrogenation and dehydrogenation mechanism of aluminum still remain unclear and fundamental study of the Al-H system is required to utilize AlH as a practical hydrogen storage material. Aluminum is hydrogenated under high pressure and high temperature to clarify the reaction mechanism. The hydrogenation and dehydrogenation process is investigated using an energy-dispersive and an angle-dispersive in situ X-ray diffraction system.
Osakabe, Toyotaka; Yamauchi, Hiroki; Okuchi, Takuo*
Koatsuryoku No Kagaku To Gijutsu, 20(1), p.72 - 75, 2010/02
A new hybrid-type anvil technique for high-pressure single-crystal magnetic neutron diffraction under 10 GPa is described. The hybrid anvil is composed of an opposed pair of two kinds of anvils. One is a large sapphire anvil or a supported SiC anvil and the other is a tungsten carbide (WC) anvil which has a hollow in the center of the culet. In a feasibility test of the hybrid anvil, we could generate the pressure up to 10 GPa at the load of 3.8 tons with high stability.
Utsumi, Wataru
Koatsuryoku No Kagaku To Gijutsu, 19(1), p.10 - 14, 2009/03
User operation of J-PARC started in December of 2008. It is expected that high pressure material science and the investigation of the Earth's interior will greatly improve using the high flux pulse neutrons of J-PARC. In this article, I introduce the current status of neutron powder diffraction beamlines and our strategy of high pressure experiments.
Arai, Masatoshi
Koatsuryoku No Kagaku To Gijutsu, 19(1), p.4 - 9, 2009/02
no abstracts in English
Machida, Akihiko; Otomo, Toshiya*; Hattori, Takanori; Fukazawa, Hiroshi
Koatsuryoku No Kagaku To Gijutsu, 19(1), p.24 - 30, 2009/02
We have investigated the fundamental properties of metal hydrides or hydrogen storage materials. The interest is focused on basic understanding of the hydrogen-metal interactions in metal hydride systems. Neutron scattering technique, which is capable of determining hydrogen positions and bonding states, is a key tool to investigate the interactions, and becomes significantly powerful when combined with high pressure technique, which realizes high hydrogen density states by compression of metal lattices. In this article, we present high-pressure neutron scattering techniques using Paris-Edinburgh cell and hydrogen-gas cell under development at J-PARC and JRR-3.
Aoki, Katsutoshi; Machida, Akihiko; Omura, Ayako*; Watanuki, Tetsu
Koatsuryoku No Kagaku To Gijutsu, 18(3), p.273 - 278, 2008/08
The highly compressed state of metal hydride has been investigated to explore structural and electronic transitions characteristic to hydride. The hydrogen atoms play the lead in the transitions, showing displacement in or transfer between the interstitial sites of a metal lattice. One example is the band gap closing observed for a long period lattice of yttrium tri-hydride, appearing at pressures above 12 GPa. Another example is photochromic event observed again for yttrium hydride. The former is likely accompanied by the in-site displacement of hydrogen atoms and the latter by the site-to-site transfer.
Komatsu, Kazuki*; Arima, Hiroshi*; Kagi, Hiroyuki*; Okuchi, Takuo*; Sasaki, Shigeo*; Yamauchi, Hiroki; Fukazawa, Hiroshi; Igawa, Naoki; Utsumi, Wataru; Kamiyama, Takashi*
Koatsuryoku No Kagaku To Gijutsu, 18(2), p.170 - 172, 2008/05
In this short communication, we report neutron diffractions under high pressure from lead powder in a Paris-Edinburgh cell at the High Resolution Powder Diffractometer (HRPD) installed at JRR-3, Ibaraki, Japan. This is the kick-off experiment in Japan as a high pressure powder diffraction study using reactor neutron source.
Hattori, Takanori
Koatsuryoku No Kagaku To Gijutsu, 17(1), p.75 - 76, 2007/02
The international workshop "crystallography at high pressures-2006", which was held at Dubna in Russia from Sept. 28th to Oct 1st., is introduced. The workshop was organized by the Commission on High Pressure of the International Union of Crystallography and the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research (JINR). About 80 participants attended the workshop and 31 oral presentations and 36 poster presentation have done. The workshop consisted of the following sessions: Simple elements, Molecular Solids, Physical Properties of Magnetic Structures, Material Sciences and high-pressure Synthesis, Mineral Physics and Geophysics, Technical developments, Organics, Liquid and amorphous Materials, Carbon and nano materials. In the conference, many noticeable studies which are unfamiliar to high-pressure scientists, such as neutron scattering or 
-ray angular correlation, were presented by the scientists in JINR. The pulse neutron source IBR-2 and the experiments which have done in that facility are also introduced.
X-ray observations with synchrotron radiationKaneko, Hiroshi*; Funakoshi, Kenichi*; Katsura, Tomoo*; Utsumi, Wataru
Koatsuryoku No Kagaku To Gijutsu, 15(1), p.9 - 14, 2005/01
This article addresses the computer control and data analysis system in "SPEED-1500", a Kawai-type multi-anvil press installed on beamline BL04B1 at the SPring-8, which is for X-ray diffraction and radiography experiments by means of synchrotron radiation. The system consists of several different computer applications, which are for pressure and temperature control, stage and goniometer control, and data-collection and its analysis. These programs have been used by many public users and are still improving.
