Self-diffusion of the oxygen ion in a ThO2 single crystal was determined at 845 to 1646C by using the gas-solid isotopic exchange technique with 18O as a tracer. The self-diffusion coefficients determined in the higher temperature range were represented by:

D(cm2/s) = 5.73 x 10-2 exp[-49900/RT]

Those determined in the lower temperature range were represented by:

D(cm2/s) = 1.00 x 10-6 exp[-17600/RT]

K.Ando, Y.Oishi, Y.Hidaka: The Journal of Chemical Physics, 1976, 65[7], 2751-5