STUDY OF GROWTH DEFECTS AND STRUCTURE IN NONLINEAR-OPTICAL CRYSTALS OF LITHIUM BORIC OXIDE

Imperfections in the (100), (010) and (001) plates of an inorganic non linear crystal of lithium boric oxide [lithium triboron (III) tetraoxi de] (LiB3O5), prepared from different blocks, have been studied by mea ns of X-ray projection topography. The experimental results show that there are mainly grown-in dislocations with b= [100], [101], [10 $$($) over bar 1], [001] and [011], glide dislocations in the system of (01 0)[101], inclusion-induced dislocations almost all with b = [101], [10 $$($) over bar 1] and [001], distributed in a network parallel to the (010) plane, inclusions with the orthorhombic configuration and a lon g stripe to which there is only one gas bubble attached, and assigned to be the negative crystals. All dislocations run nearly straight and are of the pure screw type. The origins of defect formation and some o ther crystal properties are discussed in terms of the structure.