Mictomagnetism and suppressed thermal conduction of the prototype high-entropy alloy CrMnFeCoNi

Yang, J.*; Ren, W.*; Zhao, X.*; Kikuchi, Tatsuya*; Miao, P.*; Nakajima, Kenji; Li, B.*; Zhang, Z.*

Journal of Materials Science and Technology, 99, p.55 - 60, 2022/02

https://doi.org/10.1016/j.jmst.2021.04.077

High-entropy alloys are characteristic of extensive atomic occupational disorder on high-symmetric lattices, differing from traditional alloys. Here, we investigate magnetic and thermal transport properties of the prototype face-centered-cubic high-entropy alloy CrMnFeCoNi by combining physical properties measurements and neutron scattering. Direct-current (dc) and alternating-current (ac) magnetizations measurements indicate a mictomagnetic behavior with coexisting antiferromagnetic and ferromagnetic interactions in the entire temperature region and three anomalies are found at about 80, 50, and 20 K, which are related to the paramagnetic to antiferromagnetic transition, the antiferromagnetic to ferromagnetic transition, and the spin freezing, respectively. The electrical and thermal conductivities are significantly reduced compared to Ni and the temperature dependence of lattice thermal conductivity exhibits a glass-like plateau. Inelastic neutron scattering measurements suggest weak anharmonicity so that the thermal transport is expected to be dominated by the defect scattering.

Synthesis and characterisation of a new graphitic C-S compound obtained by high pressure decomposition of CS

Klotz, S.*; Baptiste, B.*; Hattori, Takanori; Feng, S. M.*; Jin, Ch.*; Bneut, K.*; Guigner, J. M.*; Estve, I.*

Carbon, 185, p.491 - 500, 2021/11

https://doi.org/10.1016/j.carbon.2021.09.048

Carbon disulphide (CS) is one of the simplest molecular systems made of double covalent bonds. Under high pressure, the molecular structure is expected to break up to form extended crystalline or polymeric solids. Here we show that by compression at 300 K to approximately 10 GPa using large-volume high pressure techniques, an instantaneous reaction leads to a mixture of pure sulphur and a well-defined compound with stoichiometry close to CS which can be recovered to ambient pressure. We present neutron and X-ray diffraction as well as Raman data which show that this material consists of sulphur bonded to sp graphite layers of nanometric dimensions. The compound is a semiconductor with a gap of 45 meV, as revealed by temperature dependent resistivity measurements, and annealing at temperatures above 200C allow to reduce its sulphur content up to CS. Its structural and electronic properties are fundamentally different to "Bridgman black" reported from previous high pressure experiments on CS.

Multiple deformation scheme in direct energy deposited CoCrNi medium entropy alloy at 210K

Kim, Y. S.*; Chae, H.*; Woo, W.*; Kim, D.-K.*; Lee, D.-H.*; Harjo, S.; Kawasaki, Takuro; Lee, S. Y.*

Materials Science & Engineering A, 828, p.142059_1 - 142059_10, 2021/11

https://doi.org/10.1016/j.msea.2021.142059

Dynamics of water in a catalyst layer of a fuel cell by quasielastic neutron scattering

Ito, Kanae; Yamada, Takeshi*; Shinohara, Akihiro*; Takata, Shinichi; Kawakita, Yukinobu

Journal of Physical Chemistry C, 125(39), p.21645 - 21652, 2021/10

https://doi.org/10.1021/acs.jpcc.1c06014

Mechanism of strengthening in cast iron by pulsed neutron beam

Harjo, S.

Kensa Gijutsu, 26(9), p.9 - 13, 2021/09

no abstracts in English

Phase transition and chemical reactivity of 1H-tetrazole under high pressure up to 100 GPa

Gao, D.*; Tang, X.*; Wang, X.*; Yang, X.*; Zhang, P.*; Che, G.*; Han, J.*; Hattori, Takanori; Wang, Y.*; Dong, X.*; et al.

Physical Chemistry Chemical Physics, 23(35), p.19503 - 19510, 2021/09

https://doi.org/10.1039/D1CP02913D

Pressure-induced phase transition and polymerization of nitrogen-rich molecules are widely focused due to its extreme importance for the development of green high energy density materials. Here, we present a study of the phase transition and chemical reaction of 1H-tetrazole up to 100 GPa by using Raman, IR, X-ray diffraction, neutron diffraction techniques and theoretical calculation. A phase transition above 2.6 GPa was identified and the high-pressure structure was determined with one molecule in a unit cell. The 1H-tetrazole polymerizes reversibly below 100 GPa, probably through a carbon-nitrogen bonding instead of nitrogen-nitrogen bonding. Our studies updated the structure model of the high pressure phase of 1H-tetrazole, and presented the possible intermolecular bonding route for the first time, which gives new insights to understand the phase transition and chemical reaction of nitrogen-rich compounds, and benefit for designing new high energy density materials.

Hydrogen permeation property of bulk cementite

Adachi, Nozomu*; Ueno, Haruki*; Onoe, Katsuhiko*; Morooka, Satoshi; Todaka, Yoshikazu*

ISIJ International, 61(8), p.2320 - 2322, 2021/08

https://doi.org/10.2355/isijinternational.ISIJINT-2021-134

Neutron scattering study on yttrium iron garnet for spintronics

Nambu, Yusuke*; Shamoto, Shinichi

Journal of the Physical Society of Japan, 90(8), p.081002_1 - 081002_15, 2021/08

https://doi.org/10.7566/JPSJ.90.081002

no abstracts in English

Practical tests of neutron transmission imaging with a superconducting kinetic-inductance sensor

Vu, TheDang; Shishido, Hiroaki*; Aizawa, Kazuya; Kojima, Kenji M*; Koyama, Tomio*; Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Soyama, Kazuhiko; Miyajima, Shigeyuki*; et al.

Nuclear Instruments and Methods in Physics Research A, 1006, p.165411_1 - 165411_8, 2021/08

https://doi.org/10.1016/j.nima.2021.165411

Anisotropic thermal lattice expansion and crystallographic structure of strontium aluminide within Al-10Sr alloy as measured by in-situ neutron diffraction

Liss, K.-D.*; Harjo, S.; Kawasaki, Takuro; Aizawa, Kazuya; Xu, P. G.

Journal of Alloys and Compounds, 869, p.159232_1 - 159232_9, 2021/07

https://doi.org/10.1016/j.jallcom.2021.159232