天然绿柱石晶体中生长区界面的X射线形貌和光学双折射形貌研究

用X射线形貌术及光学双折射形貌术对天然绿柱石晶体中的生长区界面进行了研究。观测发现,同类生长区的界面在两种形貌中通常不出现可见的衬度;异类生长区界面中,t-s界面在X射线形貌中呈现动力学干涉条纹衬度,表明它们具有平移型界面的特征,根据消光规律知其相应的位移矢量很可能与界面垂直;在双折射形貌中,异类生长区界面衬度的出现与界面两侧存在不同的长程应变场有关。实践表明,两种形貌术互相补充,互相参证,在生长区界面的研究中是十分有效的。 关键词：

A STUDY OF GROWTH SECTOR BOUNDARIES IN NATURAL BERYLS BY X-RAY DIFFRACTION TOPOGRAPHY AND OPTICAL BIREFRINGENCE TOPOGRAPHY

The growth sector boundaries in natural beryls have been investigated by means of X-ray topography and optical birefringence topography. The boundaries of the same families usually show no contrast by the two different topography techniques. The t-s boundaries show the dynamical interference fringes in the X-ray topographs, which is characteristic for translation-type boundaries. Their displacement vectors, determined from extinction behaviour of the fringes, are probably perpendicular to the corresponding boundaries respectively. In the birefringence topographs, the contrast of the boundaries of different families is attributed to the long range strain fields on the two sides of the boundaries. From the experimental results, we may recognize that the two different topographies are complementary in the study of growth sector boundaries.