Synthesis, Structural Transformation, Thermal Stability, Valence State, and Magnetic and Electronic Properties of PbNiO3 with Perovskite- and LiNbO3-Type Structures

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• 作者：Yoshiyuki Inaguma ; Kie Tanaka ; Takeshi Tsuchiya ; Daisuke Mori ; Tetsuhiro Katsumata ; Tomonori Ohba ; Ko-ichi Hiraki ; Toshihiro Takahashi ; Hiroyuki Saitoh
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：October 26, 2011
• 年：2011
• 卷：133
• 期：42
• 页码：16920-16929
• 全文大小：1152K
• 年卷期：v.133,no.42(October 26, 2011)
• ISSN：1520-5126

文摘

We synthesized two high-pressure polymorphs PbNiO₃ with different structures, a perovskite-type and a LiNbO₃-type structure, and investigated their formation behavior, detailed structure, structural transformation, thermal stability, valence state of cations, and magnetic and electronic properties. A perovskite-type PbNiO₃ synthesized at 800 掳C under a pressure of 3 GPa crystallizes as an orthorhombic GdFeO₃-type structure with a space group Pnma. The reaction under high pressure was monitored by an in situ energy dispersive X-ray diffraction experiment, which revealed that a perovskit-type phase was formed even at 400 掳C under 3 GPa. The obtained perovskite-type phase irreversibly transforms to a LiNbO₃-type phase with an acentric space group R3c by heat treatment at ambient pressure. The Rietveld structural refinement using synchrotron X-ray diffraction data and the XPS measurement for both the perovskite- and the LiNbO₃-type phases reveal that both phases possess the valence state of Pb⁴⁺Ni²⁺O₃. Perovskite-type PbNiO₃ is the first example of the Pb⁴⁺M²⁺O₃ series, and the first example of the perovskite containing a tetravalent A-site cation without lone pair electrons. The magnetic susceptibility measurement shows that the perovskite- and LiNbO₃-type PbNiO₃ undergo antiferromagnetic transition at 225 and 205 K, respectively. Both the perovskite- and LiNbO₃-type phases exhibit semiconducting behavior.