Growth of YAG Single Crystals by Flux Method(Chemistry)

The growth of YAG single crystals by the slow cooling method using a PbO-PbF_2-B_2O_3 mixed flux was investigated. (1) The solubilities of YAG in PbO, PbF_2 and PbO-PbF_2-B_2O_3 were determined by the weight loss method in the temperature range from 800 to 1300℃. It is shown that the PbO-PbF_2-B_2O_3 mixed flux gave the largest solubility gradient but that PbO flux gave the maximum yield of YAG crystals. (2) The growth experiments were made at constant cooling rates of 1.3, 2.6, 5.2 and 10.4℃/h where the vertical temperature gradient along the crucible was varied from 0 to 15℃/cm. The optimum growth conditions were as follows ; temperature gradient : >6℃/cm, cooling rate : 1300℃. (3) The grown crystals composed of {110} with rare appearance of {211}. Observation of the growth sector of etched crystals revealed that {110} developed at the early stage of growth. (4) It is reported by previous investigators that the grown crystals dissolve in this flux system below 950℃, but no significant dissolution was observed in the solubility measurements and also in the growth process by slow cooling down to 850℃