Diffusion induced grain boundary migration (DIGM) process in ZrO2Y2O3-MgO ion conductors

Paper contains results of microstructure and chemical composition analyses of micrograins formed on initial grain boundaries in three systems: ZrO2 6 mol. % Y2O3, ZrO2 + 6 mel. % Y2O3 + 5.4 mol. % MgO and ZrO2 + 6 mol. % Y2 O3 + 12 mol. % MgO. It was found out that the micrograins appeared in the p rocess of diffusion induced grain boundary migration (DIGM). They revealed an increased level of Y2O3 content (up to 2 mol. %) and a cubic symmetry. D IGM investigations were conducted after a heat-treatment of the samples at 1500 degrees C for 50 hours and at 1700 degrees C for 2 hours. Zirconia - y ttria solid solution with magnesia particle addition showed the increase of amount of migration nuclei and the size of new-created grains. However, no change in the chemical composition of the grains was detected. The mechanical properties and ion conductivity of the material were investi gated. It was established that the ZrO2 + 6 mol. % Y2O3 ceramic heat-treate d at 1500 degrees C showed the highest grain boundary conductivity. In inve stigated system the ratio (sigma(gb)/sigma(tot)) increases with the magnesi a additive amount. This material has high hardness and slightly decreased f racture toughness. It seems to be a perspective material for solid electrol ytes.