Oxygen diffusion in single crystal yttrium aluminum garnet

Abstract

Self-diffusion coefficients of oxygen in single crystal yttrium aluminum garnet (YAG) have been measured by the gas-solid isotope exchange technique using 18O as a tracer at temperatures in the range 1060–1550δC. The volume diffusion coefficients of oxygen ions in the as-grown crystal can be expressed by D = 5.24×10 -7 exp(- 325000 J/ mol/ RT) m 2/ s. This coefficient depends on the atmosphere of heat treatment prior to diffusion annealing. This effect on their oxygen vacancy levels is ascribed to both the formation of an F-center-like defect and the valency change of an iron impurity contained. It is considered that this activation energy is due to oxygen ion migration. The oxygen vacancy concentration of a faceted region of single crystal YAG was higher than without facets.