Predicted and real habits of flux grown potassium lutetium tungstate single crystals

The laser host crystals of KLu(WO4)(2)(KLuW) with large dimensions up to 43 x 35 x 16 mm(3) have been grown along b, a*, c, and [(1) over bar 11] crystallographic directions, respectively, from the melt by the top-seeded solution growth slow-cooling method. The crystal structure was refined by using a four circle X-ray diffractometer: The unit cell parameters are a = 10.591(5) angstrom, b = 10.244(6) angstrom, c = 7.500(3) angstrom, and beta = 130.73(2)degrees with Z = 4, in space group C2/c. The experimentally grown crystal shapes developed along different crystalline directions were compared to the predicted habits, and the influences of seed orientations on the crystal growth habits, quality, and utilization ratio are analyzed by Bravais-Friedel Dormay-Harker law and PBC' theory. We found that crystals grown along c directions have higher utilization ratios and good optical qualities. Crystals with a high growth rate but worse quality along the b and a* directions can be obtained. Too flat and inner macrodefects extended from the seeds make low utilization ratios for crystals grown along the b and a* directions.