Order-disorder phenomena in the low-temperature phase ofBaTiO3
Order-disorder phenomena in the low-temperature phase ofBaTiO3
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BaTiO3低温相的有序-无序现象
DOI：
10.1103/physrevb.76.094105
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发表时间：
2007
影响因子：
3.7
通讯作者：
K. Müller
中科院分区：
文献类型：
--
作者：
G. Völkel;K. Müller
报道了在菱面体低温相中掺杂单晶的电子顺磁共振测量结果。在统计上，探针离子取代了等价态。在接近向正交相转变时观察到的临界线展宽表明，偏心的Ti亚系统内存在有序-无序过程，并形成了结构与其中一个正交相相容的动态前驱体团簇。从数据中可以看出，这是一种特殊类型的相变，它不仅在立方-四方相变中存在位移和有序-无序特征，而且在低温下在正交-菱形相变中也存在位移和有序无序特征。正交相、四方相和立方相中频谱的消失可以解释为沿身体对角线的平均偏心位置周围的瞬时偏心位置随时间的变化而引起的强线宽的结果。
- and-band electron paramagnetic resonance measurements are reported on-dopedsingle crystals in the rhombohedral low-temperature phase. Theprobe ion is statistically substitute for the isovalention. The critical line broadening observed when approaching the phase transition to the orthorhombic phase demonstrates the presence of order-disorder processes within the off-center Ti subsystem and the formation of dynamic precursor clusters with a structure compatible with one of the orthorhombic phase. From the data it is concluded thatshows a special type of phase transition where displacive and order-disorder character are not only present at the cubic-tetragonal transition, but also at the orthorhombic-rhombohedral transition at low temperatures. The disappearance of thespectrum in the orthorhombic, tetragonal, and cubic phases can be interpreted as the consequence of the strong line broadening caused by changes of the instantaneous off-center positions in time around the averaged off-center position along a body diagonal.