Saito, Hiroyuki*; Machida, Akihiko*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Sato, Toyoto*; Orimo, Shinichi*; Aoki, Katsutoshi*
Physica B; Physics of Condensed Matter, 587, p.412153_1 - 412153_6, 2020/06
The site occupancy of deuterium (D) atoms in face-centered-cubic nickel (fcc Ni) was measured along a cooling path from 1073 to 300 K at an initial pressure of 3.36 GPa via in situ neutron powder diffraction. Deuterium atoms predominantly occupy the octahedral (O) sites and slightly occupy the tetrahedral (T) sites of the fcc metal lattice. The O-site occupancy increases from 0.4 to 0.85 as the temperature is lowered from 1073 to 300 K. Meanwhile, the T-site occupancy remains c.a. 0.02. The temperature-independent behavior of the T-site occupancy is unusual, and its process is not yet understood. From the linear relation between the expanded lattice volume and D content, a D-induced volume expansion of 2.09(13) atom was obtained. This value is in agreement with the values of 2.14-2.2 atom previously reported for Ni and Ni Fe alloy.
Naoe, Takashi; Harjo, S.; Kawasaki, Takuro; Xiong, Z.*; Futakawa, Masatoshi
JPS Conference Proceedings (Internet), 28, p.061009_1 - 061009_6, 2020/02
At the J-PARC, a mercury target vessel made of 316L SS suffers proton and neutron radiation environment. The target vessel also suffers cyclic impact stress caused by the proton beam-induced pressure waves. The vessel suffers higher than 4.510 cyclic loading during the expected service life of 5000 h. We have investigated fatigue strength 316L SS up to gigacycle in the previous studies. The cyclic hardening and softening behavior were observed. In this study, to evaluate the cyclic hardening/softening behavior, the dislocation densities of specimens were measured using the neutron diffraction method at the MLF BL-19. The result showed that the dislocation density of a 316L SS was increased with increasing the number of loading cycles. By contrast, in the case of cold-rolled 316L SS, annihilation and re-accumulation of dislocation by cyclic loading were observed. In the workshop, result of neutron diffraction measurement will be introduced with the progress of fatigue test.
Harjo, S.; Kawasaki, Takuro; Grazzi, F.*; Shinohara, Takenao; Tanaka, Manako*
Materialia, 7, p.100377_1 - 100377_9, 2019/09
Fukui, Hiroshi*; Fujimoto, Manato*; Akahama, Yuichi*; Sano, Asami; Hattori, Takanori
Acta Crystallographica Section B; Structural Science, Crystal Engineering and Materials (Internet), 75(4), p.742 - 749, 2019/08
Monoclinic ZrO baddeleyite exhibits anomalous softenings of bulk modulus and atom vibrations with compression. We have investigated the pressure evolution of the structure by neutron powder diffraction combined with ab-initio calculations. The present results showed that the anomalous pressure response of the bulk modulus is related not to the change in the bonding characters but to the deformation of an oxygen sublattice, especially one of layers made of oxygens in the crystallographic * plane. The layer consists of two parallelograms; one is rotating with little distortion and the other is being distorted with increasing pressure. This deformation of this layer makes one of Zr-O distances long, resulting in the softening of some atom vibrational modes.
Kyono, Atsushi*; Kato, Masato*; Sano, Asami; Machida, Shinichi*; Hattori, Takanori
Physics and Chemistry of Minerals, 46(5), p.459 - 469, 2019/05
To reveal the decomposition mechanism with temperature under high-pressure, crystal structure of a hydrogrossular, katoite CaAl(OD) has been studied by in-situ neutron diffraction at 8 GPa. Although unusual expansion behavior was discerned at 200-400C, the unit cell was continuously expanded up to 850C. At 900C, katoite was decomposed, indicating that pressure strongly increases dehydration temperature from 300C to 900C. On release of pressure, the katoite reappear together with corundum and portlandite. At 8 GPa, CaO and AlO polyhedra expand with temperature up to 850C by about 8% and 13%, respectively. On the other hand, tetrahedral interstices are isotopically squeezed by about 10%: due to the expansion of above polyhedra. The neighboring D-D distance remains almost unchanged in this temperature range, while the O-D bond distance shrinks drastically just before decomposition. This finding suggests that the shortening of O-D distance caused by the D-D repulsion destabilizes the O-D bond, which induces the thermal decomposition of katoite.
Ikuta, Daijo*; Otani, Eiji*; Sano, Asami; Shibazaki, Yuki*; Terasaki, Hidenori*; Yuan, L.*; Hattori, Takanori
Scientific Reports (Internet), 9, p.7108_1 - 7108_8, 2019/05
Hydrogen is likely one of the light elements in the Earth's core. Despite its importance, no direct observation has been made of hydrogen in an iron lattice at high pressure. We made the first direct determination of site occupancy and volume of interstitial hydrogen in a face-centered cubic (fcc) iron lattice up to 12 GPa and 1200 K using the in situ neutron diffraction method. At pressures 5 GPa, the hydrogen content in the fcc iron hydride lattice (x) was small at x 0.3, but increased to x 0.8 with increasing pressure. Hydrogen atoms occupy both octahedral (O) and tetrahedral (T) sites; typically 0.870 in O-sites and 0.057 in T-sites at 12 GPa and 1200 K. The fcc lattice expanded approximately linearly at a rate of 2.22 per hydrogen atom, which is higher than previously estimated (1.9 /H). The lattice expansion by hydrogen dissolution was negligibly dependent on pressure. The large lattice expansion by interstitial hydrogen reduced the estimated hydrogen content in the Earth's core that accounted for the density deficit of the core. The revised analyses indicate that whole core may contain hydrogen of 80 times of the ocean mass with 79 and 0.8 ocean mass for the outer and inner cores, respectively.
Yano, Naomine*; Yamada, Taro*; Hosoya, Takaaki*; Ohara, Takashi; Tanaka, Ichiro*; Niimura, Nobuo*; Kusaka, Katsuhiro*
Acta Crystallographica Section D; Structural Biology (Internet), 74(11), p.1041 - 1052, 2018/11
Yoshida, Koji*; Inoue, Takuya*; Torigoe, Motokatsu*; Yamada, Takeshi*; Shibata, Kaoru; Yamaguchi, Toshio*
Journal of Chemical Physics, 149(12), p.124502_1 - 124502_10, 2018/09
Differential scanning calorimetry, X-ray diffraction, and quasi-elastic neutron scattering (QENS) measurements of aqueous glycine solutions confined in mesoporous silica (MCM-41) were performed at different glycine concentrations, pH, and loading ratio (= mass of glycine solution / mass of dry MCM-41) in the temperature range from 305 to 180 K to discuss the confinement effect on the thermal behavior, the structure, and the dynamic properties of the solutions.
Chanyshev, A. D.*; Litasov, K. D.*; Rashchenko, S.*; Sano, Asami; Kagi, Hiroyuki*; Hattori, Takanori; Shatskiy, A. F.*; Dymshits, A. M.*; Sharygin, I. S.*; Higo, Yuji*
Crystal Growth & Design, 18(5), p.3016 - 3026, 2018/05
The high-temperature structural properties of solid benzene were studied at 1.5-8.2 GPa up to melting or decomposition using multi-anvil apparatus and in situ neutron and X-ray diffraction. The crystal structure of deuterated benzene phase II (P2/c unit cell) was refined at 3.6-8.2 GPa and 473-873 K. Our data show a minor temperature effect on the change in the unit cell parameters of deuterated benzene at 7.8-8.2 GPa. At 3.6-4.0 GPa, we observed the deviation of deuterium atoms from the benzene ring plane and minor zigzag deformation of the benzene ring, enhancing with the temperature increase caused by the displacement of benzene molecules and decrease of van der Waals bond length between the -conjuncted carbon skeleton and the deuterium atom of adjacent molecule. Deformation of benzene molecule at 723-773 K and 3.9-4.0 GPa could be related to the benzene oligomerization at the same conditions. In the pressure range of 1.5-8.2 GPa, benzene decomposition was defined between 773-923 K. Melting was identified at 2.2 GPa and 573 K. Quenched products analyzed by Raman spectroscopy consist of carbonaceous material. The defined benzene phase diagram appears to be consistent with those of naphthalene, pyrene, and coronene at 1.5-8 GPa.
Suwa, Tomone*; Hemmi, Tsutomu*; Saito, Toru*; Takahashi, Yoshikazu*; Koizumi, Norikiyo*; Luzin, V.*; Suzuki, Hiroshi; Harjo, S.
IEEE Transactions on Applied Superconductivity, 28(3), p.6001104_1 - 6001104_4, 2018/04
Muta, Hiroaki*; Nishikane, Ryoji*; Ando, Yusuke*; Matsunaga, Junji*; Sakamoto, Kan*; Harjo, S.; Kawasaki, Takuro; Oishi, Yuji*; Kurosaki, Ken*; Yamanaka, Shinsuke*
Journal of Nuclear Materials, 500, p.145 - 152, 2018/03
Sato, Shigeo*; Kuroda, Asumi*; Sato, Kozue*; Kumagai, Masayoshi*; Harjo, S.; Tomota, Yo*; Saito, Yoichi*; Todoroki, Hidekazu*; Onuki, Yusuke*; Suzuki, Shigeru*
Tetsu To Hagane, 104(4), p.201 - 207, 2018/00
Harjo, S.; Kawasaki, Takuro; Morooka, Satoshi
Advanced Experimental Mechanics, 2, p.112 - 117, 2017/10
Akita, Koichi; Shibahara, Masakazu*; Ikushima, Kazuki*; Nishikawa, Satoru*; Furukawa, Takashi*; Suzuki, Hiroshi; Harjo, S.; Kawasaki, Takuro; Vladimir, L.*
Yosetsu Gakkai Rombunshu (Internet), 35(2), p.112s - 116s, 2017/06
Klotz, S.*; Komatsu, Kazuki*; Kagi, Hiroyuki*; Kunc, K.*; Sano, Asami; Machida, Shinichi*; Hattori, Takanori
Physical Review B, 95(17), p.174111_1 - 174111_7, 2017/05
The compression behaviour of deuterated ice VII and VIII was investigated by high pressure neutron scattering in the pressure range 2-13.7 GPa between 93 K and 300 K. We establish equations-of-state which contain accurate values for the bulk moduli B, their pressure derivatives B', as well as the ambient pressure volumina V. These equations-of-state hold over a large part of the stability domain of ice VII, by comparison with available X-ray data, and to at least 13 GPa for ice VIII. They are indistinguishable at low pressures, but beyond 7 GPa and at low temperatures ice VIII appears to become stiffer than expected. This might be related to an anomalous phonon hardening observed previously in ice VIII in this range [D.D. Klug et al., Physical Review B, 70, 144113 (2004)].
Yamauchi, Hiroki; Metoki, Naoto; Watanuki, Ryuta*; Suzuki, Kazuya*; Fukazawa, Hiroshi; Chi, S.*; Fernandez-Baca, J. A.*
Journal of the Physical Society of Japan, 86(4), p.044705_1 - 044705_9, 2017/04
Neutron diffraction experiments have been carried out to characterize the magnetic structures and order parameters in an intermediate phase of NdB showing the successive phase transitions at K, K, and K. The observed patterns in phase II () are successfully explained by postulating a planar structure with static magnetic moments in the tetragonal -plane. We have found that the magnetic structure in phase II can be uniquely determined to be a linear combination of noncolinear "all-in/all-out"-type and "vortex"-type antiferromagnetic structures. We propose that the quadrupolar interaction holds the key to stabilizing the noncollinear magnetic structure and quadrupolar order. Here, the frustration in the Shastry - Sutherland lattice would play an essential role in suppressing the dominance of the magnetic interaction.
Metoki, Naoto; Yamauchi, Hiroki; Kitazawa, Hideaki*; Suzuki, Hiroyuki*; Hagihala, Masato*; Frontzek, M. D.*; Matsuda, Masaaki*; Fernandez-Baca, J. A.*
Journal of the Physical Society of Japan, 86(3), p.034710_1 - 034710_5, 2017/03
Magnetic structure of NdPdAl has been studied by means of neutron powder diffraction. We observed remarkable magnetic reflections with the modulation vector = (1/2 0 0) below the ordering temperature = 1.2 K. We found a collinear magnetic structure of Nd moment of 2.9(1) at 0.3 K parallel to the -axis, where the ferromagnetically ordered planes stack with four Nd layer period of ++-- sequence along the direction with the distance between adjuscent Nd layers to be . This is very similar to CePdAl with = (0.23 0.23 0) and the Ce moment parallel to the -axis. These structures with in-plane modulation is a consequence of the two dimensional nature of fermi surface topology in this family, coming from unique crystal structure with very long tetragonal unit cell and large distance 7 between the rare earth layers separated by Al and two Pd layers.
Ungr, T.*; Harjo, S.; Kawasaki, Takuro; Tomota, Yo*; Ribrik, G.*; Shi, Z.*
Metallurgical and Materials Transactions A, 48(1), p.159 - 167, 2017/01
Oka, Hiroshi; Tanno, Takashi; Otsuka, Satoshi; Yano, Yasuhide; Uwaba, Tomoyuki; Kaito, Takeji; Onuma, Masato*
Nuclear Materials and Energy (Internet), 9, p.346 - 352, 2016/12
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.