BiGaO3-Based Perovskites: A Large Family of Polar Materials

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• 作者：Alexei A. Belik ; Dmitriy A. Rusakov ; Takao Furubayashi ; Eiji Takayama-Muromachi
• 刊名：Chemistry of Materials
• 出版年：2012
• 出版时间：August 14, 2012
• 年：2012
• 卷：24
• 期：15
• 页码：3056-3064
• 全文大小：580K
• 年卷期：v.24,no.15(August 14, 2012)
• ISSN：1520-5002

文摘

Solid solutions of BiGa_xM_1鈥?i>xO₃ (M = Cr, Mn, and Fe) were prepared using the high-pressure high-temperature method at 6 GPa and 1700 K (M = Cr and Fe) and 1300 K (M = Mn). The formation of a large family of polar materials with R3c and Cm symmetries was found. Crystal structures were studied with laboratory X-ray powder diffraction: space group Cm, a = 5.3150(1) 脜, b = 5.2960(1) 脜, c = 4.6965(1) 脜, and 尾 = 92.556(2)掳 for BiGa_0.4Fe_0.6O₃; space group Cm, a = 5.2798(1) 脜, b = 5.2577(1) 脜, c = 4.6465(1) 脜, and 尾 = 91.974(2)掳 for BiGa_0.7Mn_0.3O₃; space group R3c, a = 5.51623(8) 脜 and c = 13.61391(17) 脜 for BiGa_0.4Cr_0.6O₃. Samples with the Cm symmetry have square-pyramidal coordination of (Ga,M)³⁺ ions, and their structure is very similar with the structure of supertetragonal PbVO₃, BiCoO₃, and Bi₂ZnTiO₆ materials. Samples with the R3c symmetry are isostructural with BiFeO₃ and have comparable calculated (based on the point-charge model) spontaneous polarization (58 渭C/cm² for BiGa_0.4Cr_0.6O₃). The calculated polarization is 116 渭C/cm² for BiGa_0.4Fe_0.6O₃, and 102 渭C/cm² for BiGa_0.7Mn_0.3O₃. BiGa_0.4Cr_0.6O₃ has a first-order structural phase transition at 850 K, and other polar samples showed no phase transitions below decomposition temperatures. The BiGa_xMn_1鈥?i>xO₃ system demonstrated strong phase competition at 0.6 鈮?x 鈮?2/3.

Keywords:

perovskites; multiferroics; high-pressure; supertetragonality; BiFeO₃