‘Disordered’ Ba(Mg1/3Ta2/3)O3 and its ordering transition
‘Disordered’ Ba(Mg1/3Ta2/3)O3 and its ordering transition
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“无序”Ba(Mg1/3Ta2/3)O3 及其有序转变
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
G. Tendeloo
中科院分区：
文献类型：
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作者：
C. H. Lei;S. Amelinckx;G. Tendeloo
摘要 采用电子衍射和高分辨率电子显微镜（HREM）研究了原始无序Ba(Mg1/3Ta2/3)O3 (BMT)和有序热处理后BMT的显微组织。 “无序”BMT 由短程有序纳米域组成；倒易空间中存在沿所有 (111) 方向的漫反射条纹。 HREM 图像显示 BaO3 框架没有断层；缺陷发生在 B 阳离子（Mg 和 Ta）亚晶格上，由“化学缺陷”组成。此类断层改变了局部成分，导致镁或钽局部过量。两种类型故障的发生都可以保持总体 1:2 化学计量比。热处理将消除这些缺陷并产生 1:2 有序核；进一步的退火将使这些有序核变得更大，从而引发长程有序取向变异。
Abstract The microstructure of the as-received disordered Ba(Mg1/3Ta2/3)O3 (BMT) and BMT after ordering heat treatment was studied by electron diffraction and high-resolution electron microscopy (HREM). ‘Disordered’ BMT consists of short-range-ordered nanodomains; diffuse streaking along all (111) directions is present in the reciprocal space. HREM images show that the BaO3 framework is unfaulted; the defects occur on the B cation (Mg and Ta) sublattice and consist of ‘chemical faults’. Such faults change the local composition, causing a local excess of either Mg or Ta. The overall 1:2 stoichiometry can be conserved by the occurrence of both types of fault. Heat treatments will remove these faults and yield 1:2 ordered nuclei; further annealing will make these ordered nuclei grow larger, inducing long-range-ordered orientation variants.