MORPHOLOGY OF BBO CRYSTALS AND THEIR INCLUSIONS

This paper reports on the morphology and inclusions in the low tempera ture phase barium metaborate BaB2O4(BBO) crystal grown by an improved flux pulling method. The morphology of ideal BBO crystals and the rela tionship between the faces and the growth rate are given. The result t hat BBO has the symmetry L(3)3P and belongs to the space group C3v-3m can therefore be concluded. It is found that the polarity of the BBO c rystal along the Z (or c) axis has a visible influence on the morpholo gy. The investigation of the inclusions in BBO crystals shows that the se have a six-fold symmetry which corresponds to the extension of flut e-like facets. It is also found that most of the inclusions have a reg ular geometric figure and can be regarded as the negative-crystal stru cture which is due to the internal growth mechanism.