Strengthening of high-entropy alloys via modulation of cryo-pre-straining-induced defects

Wei, D.*; Gong, W.; Wang, L.*; Tang, B.*; Kawasaki, Takuro; Harjo, S.; Kato, Hidemi*

Journal of Materials Science & Technology, 129, p.251 - 260, 2022/12

https://doi.org/10.1016/j.jmst.2022.04.055

Enhancement of electrical conductivity to metallization of MnFeO spinel and postspinel with elevating pressure

Yamanaka, Takamitsu*; Rahman, S.*; Nakamoto, Yuki*; Hattori, Takanori; Jang, B. G.*; Kim, D. Y.*; Mao, H.-K.*

Journal of Physics and Chemistry of Solids, 167, p.110721_1 - 110721_10, 2022/08

https://doi.org/10.1016/j.jpcs.2022.110721

High-pressure neutron diffraction proved that MnFeO and MnFeO spinels transform into CaMnO-type structure above 18 GPa and 14 GPa, respectively. The transition pressure of MnFeO solutions decreases with increasing Mn content. Synchrotron X-ray Mssbauer experiments revealed that Fe and Fe distribution at the tetrahedral (A) and octahedral (B) sites in the spinel structure changes with pressure. MnFeO and MnFeO spinels are ferrimagnetic and the CaMnO-type phase is paramagnetic. The temperature dependence of resistivity indicates that both spinels are semiconductors wherein electrons hop between cations at the A and B sites. A pressure-induced shortening of B-B distance promoted conduction via greater electron mobility between adjacent B cations. The Fe and Fe occupancies at the B sites in MnFeO are much larger than those in MnFeO. The CaMnO-type phase is metallic. Theoretical calculation confirmed the metallic character and Fe d-orbitals strongly renormalized compared to Mn d-orbitals.

Lanthanide extraction using a thiodiglycolamic acid extractant; Effect of S-donor on lanthanide separation

Shimojo, Kojiro; Fujiwara, Iori*; Oshima, Tatsuya*; Yokoyama, Keiichi; Yaita, Tsuyoshi

Analytical Sciences, 38(7), p.1003 - 1006, 2022/07

https://doi.org/10.1007/s44211-022-00123-5

Liquid-liquid extraction of lanthanide (Ln) ions was investigated using -dioctylthiodiglycolamic acid (DOTDGAA), which is a sulfur donor ligand with an amide group and a carboxyl group connected by a thioether chain. The extraction performance and selectivity of DOTDGAA for Ln ions were compared with those of -dioctyldiglycolamic acid (DODGAA), which is also an oxygen donor ligand with a similar chemical structure, to assess the effect of the soft/hard donor atom on Ln separation. DOTDGAA quantitatively extracted all Ln ions while being selective toward light and middle Ln ions, in contrast to the selectivity of DODGAA for heavier Ln ions. Slope analysis demonstrated that the Ln transfer using DOTDGAA proceeded through a proton-exchange reaction, forming a 1:3 complex, Ln(DOTDGAA). The back-extraction of Ln ions from the extracting phase was successfully achieved under acidic conditions.

Deformation texture of bulk cementite investigated by neutron diffraction

Adachi, Nozomu*; Ueno, Haruki*; Morooka, Satoshi; Xu, P. G.; Todaka, Yoshikazu*

Materials, 15(13), p.4485_1 - 4485_7, 2022/07

https://doi.org/10.3390/ma15134485

Measurements of radiation fields from a ceramic break

Shobuda, Yoshihiro; Toyama, Takeshi*; Yoshimoto, Masahiro; Hatakeyama, Shuichiro

Proceedings of 13th International Particle Accelerator Conference (IPAC 22) (Internet), p.1663 - 1666, 2022/07

https://doi.org/10.18429/JACoW-IPAC2022-WEOZSP3

Ceramic breaks are used in synchrotrons for many purposes. For example, they are inserted between the Multi-Wire Profile Monitors (MWPMs) on the injection line at the rapid cycling synchrotron (RCS) in J-PARC to completely prevent the wall currents accompanying beams from affecting the MWPMs. On the other hand, from the viewpoint of suppressing beam impedances and the radiation fields from the ceramic breaks, it would be preferable that the inner surface of the ceramic break is coated with titanium nitride (TiN), or covered over capacitors. In this report, we measure the radiation fields from the ceramic break with and without capacitors as well as the beam profile and investigate the effect of the ceramic break on the measurements.

High-pressure neutron experiments at PLANET in J-PARC using the six-axis multi-anvil press ATSUHIME

Hattori, Takanori

Yukuatsu Gijutsu, 61(7), p.29 - 35, 2022/07

As an example of the application of hydraulic technology, the 6-axis type multi-anvil press "ATSUHIME" in the J-PARC ultra-high pressure neutron diffractometer PLANET and the research on hydrogen in the Earth's core using them are introduced.

Analysis of the electric double layer structure formed in an ionic liquid using neutron reflectivity

Tamura, Kazuhisa; Akutsu-Suyama, Kazuhiro*; Cagnes, M.*; Darwish, T. A.*

ECS Advances (Internet), 1(2), p.020503_1 - 020503_5, 2022/06

https://doi.org/10.1149/2754-2734/ac6963

The ionic liquid/Si electrode interface was investigated using neutron reflectivity. We precisely elucidated the structure of the electrical double layer formed at 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([BMIM]TFSA)/Si(100) electrode interface with the orientation of the [BMIM]TFSA molecule using a partially deuterated [BMIM]TFSA. The results revealed that [BMIM]TFSA molecules form a layered structure. Cation and anion molecules are alternatingly stacked and molecules in the first three layers are horizontally oriented to the electrode surface at E = -1.2 V, i.e., on the negatively charged electrode surface. It was also revealed that the imidazole ring in [BMIM] cation is parallel to the electrode surface.

Effect of pulsed laser irradiation on the micro-plastic behavior of radiation shielding lead glasses

Wakui, Takashi; Yamasaki, Kazuhiko*; Futakawa, Masatoshi

Jikken Rikigaku, 22(2), p.96 - 104, 2022/06

Pulsed laser irradiation and indentation tests on radiation shielding glasses and a lead-free glass were carried out. The size of irradiation damage of the glass with high lead content was larger than that with low content. The micro plastic behavior of glasses was quantitatively determined using the inverse analyses based on indentation results. Flow stress decreased with an increase of lead content and that in irradiated area was lower than that in unirradiated area. On the other hand, plastic flow resistance increased with an increase of the lead content and that in irradiated area was higher than that in unirradiated area. Fracture energy and critical size of plastic zone around tip of crack in unirradiated and irradiated areas were calculated based on experimental results including constants evaluated using the inverse analysis. These values decreased with an increase of the lead content and these values in irradiated area were lower than that in unirradiated area.

Various ordered states in Heisenberg FCC antiferromagnets with dipole-dipole interactions

Yokota, Terufumi

Journal of the Physical Society of Japan, 91(6), p.064003_1 - 064003_7, 2022/06

https://doi.org/10.7566/JPSJ.91.064003

Beam emittance growth due to the strong space-charge field at low energy of a high-intensity ion linac and its mitigation using an octupole magnetic field

Chimura, Motoki; Harada, Hiroyuki; Kinsho, Michikazu

Progress of Theoretical and Experimental Physics (Internet), 2022(6), p.063G01_1 - 063G01_26, 2022/06

https://doi.org/10.1093/ptep/ptac077

In the low-energy region of a high-intensity ion linac, a strong space-charge field causes a rapid beam emittance growth over a short distance of only few meters. The beam emittance growth leads to a beam loss and the machine activation raising a serious issue for regular maintenance of the accelerator component and beam power ramp up. In this work, we studied the mechanism of beam emittance growth due to the space-charge field based on three-dimensional particle-tracking simulation and theoretical considerations. Numerical simulations done for the high-intensity linac at J-PARC shows that the nonlinear terms in the space-charge field directly cause a beam emittance growth and beam halo formation. Then, we also propose a method to mitigate the beam emittance growth by using an octupole magnetic field, which arises as one of the nonlinear terms in the space-charge field. By applying this method in the simulation, we have succeeded mitigating the beam emittance growth.