title: Hydrogen ordering and new polymorph of layered perovskite oxyhydrides: Sr₂VO(4-x)H(x).
abstract: Compositionally tunable vanadium oxyhydrides Sr2VO(4-x)H(x) (0 ≤ x ≤ 1.01) without considerable anion vacancy were synthesized by high-pressure solid-state reaction. The crystal structures and their properties were characterized by powder neutron diffraction, synchrotron X-ray diffraction, thermal desorption spectroscopy, and first-principles density functional theory (DFT) calculations. The hydrogen anions selectively replaced equatorial oxygen sites in the VO6 layers via statistical substitution of hydrogen in the low x region (x < 0.2). A new orthorhombic phase (Immm) with an almost entirely hydrogen-ordered structure formed from the K2NiF4-type tetragonal phase with x > 0.7. Based on the DFT calculations, the degree of oxygen/hydrogen anion ordering is strongly correlated with the bonding interaction between vanadium and the ligands.
authors.affiliation: Materials and Structures Laboratory, ‡Materials Research Center for Element Strategy, and ∥Frontier Research Center, Tokyo Institute of Technology , Yokohama 226-8503, Japan.
authors.forename: Joonho
authors.initials: J
authors.lastname: Bang
authors.forename: Satoru
authors.initials: S
authors.lastname: Matsuishi
authors.forename: Haruhiro
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authors.lastname: Hiraka
authors.forename: Fumika
authors.initials: F
authors.lastname: Fujisaki
authors.forename: Toshiya
authors.initials: T
authors.lastname: Otomo
authors.forename: Sachiko
authors.initials: S
authors.lastname: Maki
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Yamaura
authors.forename: Reiji
authors.initials: R
authors.lastname: Kumai
authors.forename: Youichi
authors.initials: Y
authors.lastname: Murakami
authors.forename: Hideo
authors.initials: H
authors.lastname: Hosono