Neutron Powder Diffraction Study on the Crystal and Magnetic Structures of BiCoO3

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• 作者：Alexei A. Belik ; Satoshi Iikubo ; Katsuaki Kodama ; Naoki Igawa ; Shin-ichi Shamoto ; Seiji Niitaka ; Masaki Azuma ; Yuichi Shimakawa ; Mikio Takano ; Fujio Izumi ; and Eiji Takayama-Muromachi
• 刊名：Chemistry of Materials
• 出版年：2006
• 出版时间：February 7, 2006
• 年：2006
• 卷：18
• 期：3
• 页码：798 - 803
• 全文大小：202K
• 年卷期：v.18,no.3(February 7, 2006)
• ISSN：1520-5002

文摘

The crystal and magnetic structures of polycrystalline BiCoO₃ have been determined by the Rietveldmethod from neutron diffraction data measured at temperatures from 5 to 520 K. BiCoO₃ (space groupP4mm; Z = 1; a = 3.72937(7) Å and c = 4.72382(15) Å at room temperature; tetragonality c/a = 1.267)is isotypic with BaTiO₃ and PbTiO₃ in the whole temperature range. BiCoO₃ is an insulator with a Néeltemperature of 470 K. A possible model for antiferromagnetic order is proposed with a propagationvector of k = (¹/₂, ¹/₂, 0). In this model, magnetic moments of Co³⁺ ions are parallel to the c directionand align antiferromagnetically in the ab plane. The antiferromagnetic ab layers stack ferromagneticallyalong the c axis, forming a C-type antiferromagnetic structure. Refined magnetic moments at 5 and 300K are 3.24(2)_B and 2.93(2)_B, respectively. The structure refinements revealed no deviation fromstoichiometry in BiCoO₃. BiCoO₃ decomposed in air above 720 K to give Co₃O₄ and sillenite-like Bi₂₅CoO₃₉.