Single crystal growth of ZnWO4 by the Czochralski method and characterization

Single crystals of ZnWO4 with [100], [010] and [001] directions were successfully grown by the Czochralski method. The seed crystals for the single crystal growth of ZnWO4 could be induced by the crystal growth using platinum wires applied by the capillary action from the melt. The growth conditions in each direction were investigated in terms of the variations of rotation speed, pulling rate and diameter of the grown crystals. The formation of cracking in the grown crystals during the cooling process could be prevented by annealing effect. The growth directions of the grown crystals were determined using Laue back reflection. The microscopic characteristics of the grown crystals in each direction were discussed, and their physical properties were evaluated for hardness, thermal expansion coefficients and dielectric constants.