Local structure in BaTiO3-BiScO3 dipole glasses
Local structure in BaTiO3-BiScO3 dipole glasses
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DOI：
10.1103/physrevb.93.104106
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发表时间：
2016-03-14
影响因子：
3.7
通讯作者：
Torrejon, D.
中科院分区：
文献类型：
--
作者：
Levin, I.;Krayzman, V.;Torrejon, D.
用变温X射线/中子全散射、扩展X射线吸收精细结构和电子衍射方法研究了立方钙钛矿型（Ba_（0.6）Bi_（0.4））（Ti_（0.6）Sc_（0.4））O_（3-）固溶体的局域结构。这些数据同时拟合使用反向蒙特卡罗算法提供瞬时原子配置，已被用来提取局部位移的组成物种。较小的Bi和Ti原子呈现出分别由14个和8个分裂位点组成的概率密度分布。相反，Ba和Sc具有单位点分布。多位分布源于Bi和Ti的大且强各向异性的偏心位移。阳离子位移在短范围内相关，相关长度受化学无序的限制。这些位移的大小和它们的各向异性，这在很大程度上是由当地的化学，从室温冷却时变化相对不显着。该结构具有非随机分布的局部极化与低维极性集群，是几个单位细胞的大小。在外加电场下原子对分布函数的原位测量被用来研究场致局部结构的变化;然而，除了在电场方向上的晶格膨胀之外，在高达4 kVmm（-1）的电场值下没有观察到显著的影响。
Local structures in cubic perovskite-type (Ba0.6Bi0.4)(Ti0.6Sc0.4)O-3 solid solutions that exhibit reentrant dipole glass behavior have been studied with variable-temperature x-ray/neutron total scattering, extended x-ray absorption fine structure, and electron diffraction methods. Simultaneous fitting of these data using a reverse Monte Carlo algorithm provided instantaneous atomic configurations, which have been used to extract local displacements of the constituent species. The smaller Bi and Ti atoms exhibit probability density distributions that consist of 14 and 8 split sites, respectively. In contrast, Ba and Sc feature single-site distributions. The multisite distributions arise from large and strongly anisotropic off-center displacements of Bi and Ti. The cation displacements are correlated over a short range, with a correlation length limited by chemical disorder. The magnitudes of these displacements and their anisotropy, which are largely determined by local chemistry, change relatively insignificantly on cooling from room temperature. The structure features a nonrandom distribution of local polarization with low-dimensional polar clusters that are several unit cells in size. In situ measurements of atomic pair-distribution function under applied electric field were used to study field-induced changes in the local structure; however, no significant effects besides lattice expansion in the direction of the field could be observed up to electric-field values of 4 kVmm(-1).