磷酸铝(AlPO4)晶体中缺陷的X射线形貌研究

用X射线衍射形貌法研究了AlPO₄晶体中的微观缺陷。在所研究的晶体中,主要晶体缺陷是生长层,沉淀物和位错。位错密度在晶体表面附近最大,晶体中部较低。位错主要起源于热应力和由沉淀物或生长层所造成的晶格畸变。多数位错的柏氏矢量是b=(a+c)<1123>型,部分的是b=a[2110]。分析了晶体缺陷与生长条件之间的关系。控制生长过程中的温度波动,特别是晶体出炉时的冷却速度,对提高晶体完美性是重要的。关键词：

X-RAY DIFFRACTION TOPOGRAPHY STUDY OF DEFECTS IN AlPO4 CRYSTALS

The microscopic defects in AlPO₄ crystals have been studied by means of X-Ray diffraction topography. It was found that the major defects in these crystals are growth layers, precipitaties and dislocations. The density of dislocations is maximum near the crystal surface, and is less in the center of the crystal. The dislocation originates in thermal stress and the latticdistortion induced by the precipitaties or growth layers. The Burgers vector of most of dislocations is of the type b=(a+c) 〈1123〉, and that of the others is b=a[2110]. The relationship between growth conditions and crystal defects are analysed. We think that for improving the perfection of crystals, it is important to control temperature fluctuation during crystal growth, and especially the cooling rate after the growth process.