Effects of the grain boundary and its movement on the oxygen self-diffusion in CeO 2ZrO 2 solid solutions

Abstract

The effects of grain boundaries and their movement on the self-diffusion of oxygen ions were studied in polycrystalline solid solutions of fluorite-type 90mol% CeO2-10mol% ZrO2 and tetragonal 14mol% CeO2-86mol% ZrO2. Oxygen self-diffusion coefficients were determined using a gas-solid isotope exchange technique and measuring the time dependence of the 18O concentration in the gas phase. The oxygen self-diffusion coefficients were determined at 1570 and 1670K.The oxygen self-diffusion was not enhanced by the presence of grain boundaries. However, when rapid movement of grain boundaries due to rapid grain growth occurred, the oxygen self-diffusion was enhanced. The cause of this was interpreted as being due to the creation of a fast diffusion layer in the vicinity of the grain boundaries. The fast diffusion layer was considered to be effective in enhancement of the diffusion not only of the oxygen ions but also of the cations in the oxides.