Origin of the Monoclinic-to-Monoclinic Phase Transition and Evidence for the Centrosymmetric Crystal Structure of BiMnO3
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- 作者：Alexei A. Belik ; Satoshi Iikubo ; Tadahiro Yokosawa ; Katsuaki Kodama ; Naoki Igawa ; Shinichi Shamoto ; Masaki Azuma ; Mikio Takano ; Koji Kimoto ; Yoshio Matsui ; Eiji Takayama-Muromachi
- 刊名：Journal of the American Chemical Society
- 出版年：2007
- 出版时间：January 31, 2007
- 年：2007
- 卷：129
- 期：4
- 页码：971 - 977
- 全文大小：333K
- 年卷期：v.129,no.4(January 31, 2007)
- ISSN：1520-5126
文摘
Structural properties of polycrystalline single-phased BiMnO3 samples prepared at 6 GPa and1383 K have been studied by selected area electron diffraction (SAED), convergent beam electron diffraction(CBED), and the Rietveld method using neutron diffraction data measured at 300 and 550 K. The SAEDand CBED data showed that BiMnO3 crystallizes in the centrosymmetric space group C2/c at 300 K. Thecrystallographic data are a = 9.5415(2) Å, b = 5.61263(8) Å, c = 9.8632(2) Å, 
= 110.6584(12)
at 300K and a = 9.5866(3) Å, b = 5.59903(15) Å, c = 9.7427(3) Å, = 108.601(2) at 550 K, Z = 8, space groupC2/c. The analysis of Mn-O bond lengths suggested that the orbital order present in BiMnO3 at 300 Kmelts above TOO = 474 K. The phase transition at 474 K is of the first order and accompanied by a jumpof magnetization and small changes of the effective magnetic moment and Weiss temperature, 
eff = 4.69Band 
= 138.0 K at 300-450 K and eff = 4.79B and = 132.6 K at 480-600 K.
= 110.6584(12) at 300K and a = 9.5866(3) Å, b = 5.59903(15) Å, c = 9.7427(3) Å, = 108.601(2) at 550 K, Z = 8, space groupC2/c. The analysis of Mn-O bond lengths suggested that the orbital order present in BiMnO3 at 300 Kmelts above TOO = 474 K. The phase transition at 474 K is of the first order and accompanied by a jumpof magnetization and small changes of the effective magnetic moment and Weiss temperature, eff = 4.69Band = 138.0 K at 300-450 K and eff = 4.79B and = 132.6 K at 480-600 K.