Local structure and the phase transitions of BaTiO3
Local structure and the phase transitions of BaTiO3
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DOI：
10.1080/00150199808009173
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发表时间：
1998-01-01
期刊：
影响因子：
0.8
通讯作者：
Kraizman, V
中科院分区：
文献类型：
--
作者：
Ravel, B;Stern, EA;Kraizman, V
我们测量并分析了BaTiO3在钡k边缘处的扩展X射线吸收精细结构（EXAFS）和在钛K边缘处的X射线吸收近边缘结构（XANES）。我们的结构数据表明，随着温度升高，这种材料中的相变顺序可以通过域的无序性来解释，其中局部结构环境在两个金属位点周围的所有温度下都保持近似菱面体扭曲。随着温度升高，这些局部畸变之间的长程相关性发生变化，从而导致观察到的相变序列。我们的测量证实了用于解释 BaTiO3 相图的八位无序模型。我们表明，EXAFS 和 XANES 是伴随铁电性的局部结构扭曲的大小和方向的敏感探针，因此是铁电性微观机制的敏感探针。
We have measured and analyzed the Extended X-ray Absorption Fine Structure (EXAFS) of BaTiO3 at the barium k edge and the X-ray Absorption Near Edge Structure (XANES) at the titanium K edge. Our structural data show that the sequence of phase transitions in this material as the temperature increases is explained by a disordering of domains wherein the local structural environment remains approximately rhombohedrally distorted at all temperatures around both metal sites. As the temperature is raised, the long range correlations between these local distortions change, resulting in the observed sequence of phase transitions. Our measurements confirm the model of eight-site disorder used to explain the phase diagram of BaTiO3. We show that EXAFS and XANES are sensitive probes of both the magnitude and direction of the local structural distortions which accompany ferroelectricity and therefore are sensitive probes of the microscopic mechanism of ferroelectricity.