High quality single crystal growth of a novel superconductor UTe; Improvement of and multiple superconducting phase diagram

Sakai, Hironori; Haga, Yoshinori

Kotai Butsuri, 58(10), p.529 - 536, 2023/10

We have succeeded to grow high-quality UTe single crystals with excess uranium through molten salt flux method. We have also studied the superconducting phase diagram using the high-quality crystal applying the fields up to 25 T along the magnetic hard axis.

Development of an iron(II) complex exhibiting thermal- and photoinduced double proton-transfer-coupled spin transition in a short hydrogen bond

Nakanishi, Takumi*; Hori, Yuta*; Shigeta, Yasuteru*; Sato, Hiroyasu*; Kiyanagi, Ryoji; Munakata, Koji*; Ohara, Takashi; Okazawa, Atsushi*; Shimada, Rintaro*; Sakamoto, Akira*; et al.

Journal of the American Chemical Society, 145(35), p.19177 - 19181, 2023/08

https://doi.org/10.1021/jacs.3c06323

Observation of proton-transfer-coupled spin transition by single-crystal neutron-diffraction measurement

Nakanishi, Takumi*; Hori, Yuta*; Shigeta, Yasuteru*; Sato, Hiroyasu*; Wu, S.-Q.*; Kiyanagi, Ryoji; Munakata, Koji*; Ohara, Takashi; Sato, Osamu*

Physical Chemistry Chemical Physics, 25(17), p.12394 - 12400, 2023/05

https://doi.org/10.1039/D3CP00527E

Single crystal growth of superconducting UTe by molten salt flux method

Sakai, Hironori; Opletal, P.; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Tokunaga, Yo; Kambe, Shinsaku; Haga, Yoshinori

Physical Review Materials (Internet), 6(7), p.073401_1 - 073401_10, 2022/07

https://doi.org/10.1103/PhysRevMaterials.6.073401

The molten salt flux method is applied as a new synthetic route for the single crystals of the spin-triplet superconductor UTe. The single crystals under an optimized growth condition with excess uranium exhibit a superconducting transition at K, which is the highest reported for this compound. The obtained crystals show a remarkably large residual resistivity ratio with respect to the room temperature value and a small residual electronic contribution in specific heat well below . These results indicate that the increase of in UTe can be achieved by reducing the disorder associated with uranium vacancies. The excess uranium in the molten salt acts as a reducing agent, preventing tetravalent uranium from becoming pentavalent and suppressing creation of uranium vacancies. At the same time, the relatively low growth temperature can suppress Te volatilization.

Single-crystal structure analysis of non-deuterated triglycine sulfate by neutron diffraction at 20 and 298 K; A New disorder model for the 298 K structure

Terasawa, Yukana*; Ohara, Takashi; Sato, Sota*; Yoshida, Satoshi*; Asahi, Toru*

Acta Crystallographica Section E; Crystallographic Communications (Internet), 78(3), p.306 - 312, 2022/03

https://doi.org/10.1107/S2056989022000858

Magnetic phase diagram of helimagnetic Ba(FeSc)O (0 x 0.2) hexagonal ferrite

Maruyama, Kenichi*; Tanaka, Seiya*; Kiyanagi, Ryoji; Nakao, Akiko*; Moriyama, Kentaro*; Ishikawa, Yoshihisa*; Amako, Yasushi*; Iiyama, Taku*; Futamura, Ryusuke*; Utsumi, Shigenori*; et al.

Journal of Alloys and Compounds, 892, p.162125_1 - 162125_8, 2022/02

https://doi.org/10.1016/j.jallcom.2021.162125

synchrotron radiation observation of deformation and annealing processes of aluminum single crystal

Shiro, Ayumi*; Okada, Tatsuya*; Shobu, Takahisa

Mechanical Engineering Journal (Internet), 8(6), p.21-00106_1 - 21-00106_8, 2021/12

https://doi.org/10.1299/mej.21-00106

The objective of the present study was to carry out observations of deformation and annealing processes of aluminum single crystals using a synchrotron radiation X-rays at SPring-8. Al single-crystalline samples having a 111 orientation parallel to the longitudinal direction were grown by a Bridgman method. The samples were deformed in tension to a nominal strain of 0.08 at room temperature using an in-line tensioning apparatus. Post-deformation annealing at 480 C was subsequently carried out in the same apparatus. A two-dimensional detector was used to detect multiple diffracted beams from the sample during the deformation and annealing processes. The volume irradiated by the X-ray beam was found to be composed of three regions having a small orientation difference, which was attributable to sub-grained microstructures of the sample. Detailed analyses of a diffraction spot intensity showed that the sub-grained microstructures were surpassed by dislocated microstructures with the increase in the tensile strain. During the post-deformation annealing, diffraction spots from a recrystallized grain first appeared at 180 s after the temperature reached 480 C. Coexistence of diffraction spots from the deformation matrix and recrystallized grain lasted only for about 22 s in the irradiated volume. The migration rate of the boundary between the deformation matrix and recrystallized grain was estimated to be of the order of several micrometers/s.

Correlated Li-ion migration in the superionic conductor LiGePS

Yajima, Takeshi*; Hinuma, Yoyo*; Hori, Satoshi*; Iwasaki, Rui*; Kanno, Ryoji*; Ohara, Takashi; Nakao, Akiko*; Munakata, Koji*; Hiroi, Zenji*

Journal of Materials Chemistry A, 9(18), p.11278 - 11284, 2021/05

https://doi.org/10.1039/D1TA00552A

Successive phase transitions in IrSn (: La and Ce) investigated using neutron and X-ray diffraction

Nakazato, Seiya*; Iwasa, Kazuaki*; Hashimoto, Daisuke*; Shiozawa, Mami*; Kuwahara, Keitaro*; Nakao, Hironori*; Sagayama, Hajime*; Ishikado, Motoyuki*; Ohara, Takashi; Nakao, Akiko*; et al.

JPS Conference Proceedings (Internet), 30, p.011128_1 - 011128_6, 2020/03

https://doi.org/10.7566/JPSCP.30.011128

Time-controlled synthesis of the 3D coordination polymer U(1,2,3-Hbtc) followed by the formation of molecular poly-oxo cluster {} containing hemimellitate uranium(IV)

Dufaye, M.*; Martin, N. P.*; Duval, S.*; Volkringer, C.*; Ikeda, Atsushi; Loiseau, T.*

RSC Advances (Internet), 9(40), p.22795 - 22804, 2019/07

AA2019-0270.pdf:1.14MB

https://doi.org/10.1039/C9RA03707A

Two coordination compounds bearing tetravalent uranium (UIV)) were synthesized in the presence of tritopic hemimellitic acid in acetonitrile with a controlled amount of water (HO/U 8) and structurally characterized. The slow hydrolysis reaction together with the partial decomposition of the starting organic reactants into oxalate and acetate molecules induces the generation of such a large poly-oxo cluster with fourteen uranium centers. Structural comparisons with other closely related uranium-containing clusters, such as the {}O] with three dinuclear sub-units {}, were performed.