Investigation of the Variables Controlling the Flux Growth of High Quality Laser Crystals

摘要

A study was made of the solution variables, crystal constants, and system parameters which control the growth of large perfect crystals of refractory oxides from fused salt solvents. A set of formulas were developed for the prediction of growth conditions from these fluxes. Cooling rates, thermal gradients, stirring rates, and container dimensions were considered as system parameters. Solubilities, diffusion constants, viscosities, interfacial surface energies, solution and crystal densities, and solute radii were considered as independent variables. The formulas were applied to the prediction of crystal growing conditions for the production of sapphire and ruby from a lanthanum fluoride-aluminum oxide flux. The study included experimental determinations of the densities and viscosities of the lanthanum fluoride-aluminum oxide flux and experiments upon the solubility of aluminum oxide in this flux. Results from the program indicate that past and present difficulties with the fused salt technique of crystal growth have been caused primarily by hydrodynamic factors which may be overcome by detailed planning of experimental growth conditions. (Author)