The tracer diffusion coefficient of oxide ions in single crystals was measured by using the gas-solid isotopic exchange technique with 18O tracer. Least-squares analysis of tracer diffusion coefficients under an oxygen pressure of 4.5 x 103Pa gave:

D(cm2/s) = 3.6 x 104 exp[-310(kJ/mol)/RT]

S.Yamauchi, T.Ishigaki, J.Mizusaki, K.Fueki: Solid State Ionics, 1983, 9-10[2], 997-1000