Structural Evolution and Properties of Solid Solutions of Hexagonal InMnO3 and InGaO3

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• 作者：Dmitriy A. Rusakov ; Alexei A. Belik ; Stanislav Kamba ; Maxim Savinov ; Dmitry Nuzhnyy ; Taras Kolodiazhnyi ; Kazunari Yamaura ; Eiji Takayama-Muromachi ; Fedir Borodavka ; Jan Kroupa
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：April 18, 2011
• 年：2011
• 卷：50
• 期：8
• 页码：3559-3566
• 全文大小：1073K
• 年卷期：v.50,no.8(April 18, 2011)
• ISSN：1520-510X

文摘

Solid solutions InMn_1鈭?i>xGa_xO₃ (0 鈮?x 鈮?1) have been investigated using magnetic, dielectric, specific heat, differential scanning calorimetry (DSC), and high-temperature powder synchrotron X-ray diffraction (HT-SXRD) measurements. It was found that samples with 0.5 鈮?x 鈮?1 crystallize in space group P6₃/mmc with a 3.32 脜 and c 11.9 脜, and samples with 0.0 鈮?x 鈮?0.4 crystallize in space group P6₃cm with a 5.8 脜 and c 11.6 脜 at room temperature. HT-SXRD data revealed the existence of a P6₃cm-to-P6₃/mmc phase transition at about 480 K in InMn_0.6Ga_0.4O₃ and at 950 K in InMn_0.7Ga_0.3O₃. However, no dielectric, phonon, second-harmonic-generation, or DSC anomalies were found to be associated with these phase transitions. The phase transition should be improper ferroelectric from the symmetry point of view, but the above-mentioned experimental facts, together with the absence of ferroelectric hysteresis loops, revealed no evidence for ferroelectricity in the low-temperature P6₃cm structure. We suggest that InMn_1鈭?i>xGa_xO₃ corresponds to a nonferroelectric phase of hexagonal RMnO₃ with P6₃cm symmetry. The antiferromagnetic phase-transition temperature decreases from 118 K for x = 0 to 105 K for x = 0.1 and 73 K for x = 0.2, and no long-range magnetic ordering could be found for x 鈮?0.3. Specific heat anomalies associated with short-range magnetic ordering were observed for 0.0 鈮?x 鈮?0.5. InMn_1鈭?i>xGa_xO₃ with small Mn contents (0.8 鈮?x 鈮?0.98) has a bright-blue color.