Formation processes and crystal growth kinetics of yttrium and lanthanum aluminates in the presence of sodium oxide

Na2O effect on the processes of crystallization and yttrium and lanthanum aluminate formation in systems Y2O3(La2O3)-Al2O3 is studied. Isothermal cross sections of thernary systems Y2O3(La2O3)-Al2O3-Na2O are constructed and fields for compound existence are determined; limiting solid solutions based on lanthanum and sodium β-aluminas containing about 85-95 and 90-95 mass% of Al2O3 correspondingly are established. LaAl11O18 monocrystals are grown up. It is established that Na2O introduction into the composition of the initial mixture decreases crystallization temperature of finish material by ∼ 100-150 deg C and increases the rate of fine dispersed monomineral powder formation. When forming alumoyttrium garnet when introducing Na2O, the growth of Y3Al5O12 crystal grains increases, and the limiting size of the grain is reached at lower temperatures. 20 refs.; 5 figs.; 1 tab