Synthesis, Direct Formation under High Pressure, Structure, and Electronic Properties of LiNbO3-type Oxide PbZnO3

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• 作者：Daisuke Mori ; Kie Tanaka ; Hiroyuki Saitoh ; Takumi Kikegawa ; Yoshiyuki Inaguma
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：December 7, 2015
• 年：2015
• 卷：54
• 期：23
• 页码：11405-11410
• 全文大小：357K
• ISSN：1520-510X

文摘

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 Pb⁴⁺Zn²⁺O₃ valence state. Polarization could evolve as a result of the repulsion between constituent cations because PbZnO₃ does not contain a stereochemical 6s² cation or a Jahn鈥揟eller active d⁰ cation. Distortion of ZnO₆ octahedra resulting from cation shift is comparable with that of d⁰ 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.