期刊
JOURNAL OF APPLIED PHYSICS
卷 110, 期 2, 页码 -出版社
AMER INST PHYSICS
DOI: 10.1063/1.3606500
关键词
-
资金
- UGC, India
- Technical University of Darmstadt, Germany
- DST
Presented here are the results of Rietveld analysis of powder neutron diffraction data, which reveal that both the ferroelectric and antiferrodistortive phase transitions occur together at T similar to 925 K during heating, leading to a change in crystal structure from room temperature rhombohedral phase in the R3c space group with tilted oxygen octahedra to the high temperature paraelectric and paraelastic cubic phase in Pm (3) over barm space group. The presence of superlattice peaks due to antiphase rotation of oxygen octahedra in the rhombohedral phase until the transition to the cubic phase precludes the possibility of an intermediate R3m space group, conjectured previously on the basis of an x-ray powder diffraction study. Discontinuous change in the unit-cell volume, tilt angle, and bond lengths at the transition temperature T-C, and phase coexistence of R3c and Pm (3) over barm over 100 K range across T-C, suggest that the transition is of first order. It is argued that the R3c to Pm (3) over barm phase transition is of trigger type involving simultaneous condensation of Gamma(-)(4) and R-4(+) modes. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3606500]
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据