title: Synthesis, Direct Formation under High Pressure, Structure, and Electronic Properties of LiNbO3-type Oxide PbZnO3.
abstract: A novel LiNbO3-type (LN-type) lead zinc oxide, PbZnO3, was successfully synthesized under high pressure and temperature. Rietveld structure refinement using synchrotron powder X-ray diffraction (XRD) data demonstrated that LN-type PbZnO3 crystallized into a trigonal structure with a polar space group (R3c). The bond valence sum estimated from the interatomic distances indicated that the sample possesses a Pb(4+)Zn(2+)O3 valence state. Polarization could evolve as a result of the repulsion between constituent cations because PbZnO3 does not contain a stereochemical 6s(2) cation or a Jahn-Teller active d(0) cation. Distortion of ZnO6 octahedra resulting from cation shift is comparable with that of d(0) TiO6 in ZnTiO3 and MnTiO3 with LN-type oxides, which leads to stabilization of the polar structure. PbZnO3 exhibited metallic behavior and temperature-independent diamagnetic character. In situ XRD measurement revealed that the formation of LN-type PbZnO3 occurred directly without the formation of a perovskite phase, which is unusual among LN-type materials obtained by high-pressure synthesis.
authors.affiliation: Department of Chemistry, Faculty of Science, Gakushuin University , 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Mori
authors.affiliation: Department of Chemistry, Faculty of Science, Gakushuin University , 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan.
authors.forename: Kie
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Quantum Beam Science Center, Japan Atomic Energy Agency , 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Saitoh
authors.affiliation: Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK) , 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Kikegawa
authors.affiliation: Department of Chemistry, Faculty of Science, Gakushuin University , 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Inaguma