Crystal and Magnetic Structures of Double Hexagonal Close-Packed Iron Deuteride

Hiroyuki Saitoh; Akihiko Machida; Riko Iizuka-Oku; Takanori Hattori; Asami Sano-Furukawa; Ken-Ichi Funakoshi; Toyoto Sato; Shin-Ichi Orimo; Katsutoshi Aoki

doi:10.1038/s41598-020-66669-4

Crystal and Magnetic Structures of Double Hexagonal Close-Packed Iron Deuteride

Sci Rep. 2020 Jun 18;10(1):9934. doi: 10.1038/s41598-020-66669-4.

Authors

Hiroyuki Saitoh¹, Akihiko Machida², Riko Iizuka-Oku³, Takanori Hattori⁴, Asami Sano-Furukawa⁴, Ken-Ichi Funakoshi⁵, Toyoto Sato⁶, Shin-Ichi Orimo^{6

7}, Katsutoshi Aoki⁸

Affiliations

¹ Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5148, Japan. saito.hiroyuki@qst.go.jp.
² Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5148, Japan.
³ Geochemical Research Center, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
⁴ J-PARC Center, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki, 319-1195, Japan.
⁵ Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, Shirakata, 162-1, Shirakata, Tokai, Naka, Ibaraki, 319-1106, Japan.
⁶ Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan.
⁷ WPI-Advanced Institute for Materials Research (AIMR), Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai, 980-8577, Japan.
⁸ Geochemical Research Center, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan. k-aoki@eqchem.s.utokyo.ac.jp.

Abstract

Neutron powder diffraction profiles were collected for iron deuteride (FeD_x) while the temperature decreased from 1023 to 300 K for a pressure range of 4-6 gigapascal (GPa). The ε' deuteride with a double hexagonal close-packed (dhcp) structure, which coexisted with other stable or metastable deutrides at each temperature and pressure condition, formed solid solutions with a composition of FeD_0.68(1) at 673 K and 6.1 GPa and FeD_0.74(1) at 603 K and 4.8 GPa. Upon stepwise cooling to 300 K, the D-content x increased to a stoichiometric value of 1.0 to form monodeuteride FeD_1.0. In the dhcp FeD_1.0 at 300 K and 4.2 GPa, dissolved D atoms fully occupied the octahedral interstitial sites, slightly displaced from the octahedral centers in the dhcp metal lattice, and the dhcp sequence of close-packed Fe planes contained hcp-stacking faults at 12%. Magnetic moments with 2.11 ± 0.06 μ_B/Fe-atom aligned ferromagnetically in parallel on the Fe planes.