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Hydrogen Ordering and New Polymorph of Layered Perovskite Oxyhydrides: Sr2VO4–xHx
- Bang, Joonho, Matsuishi, Satoru, Hiraka, Haruhiro, Fujisaki, Fumika, Otomo, Toshiya, Maki, Sachiko, Yamaura, Jun-ichi, Kumai, Reiji, Murakami, Youichi, Hosono, Hideo
- Journal of the American Chemical Society 2014 v.136 no.20 pp. 7221-7224
- X-ray diffraction, anions, crystal structure, desorption, hydrogen, hydrogen bonding, ligands, oxygen, spectroscopy, vanadium
- Compositionally tunable vanadium oxyhydrides Sr₂VO₄–ₓHₓ (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.