Oxygen self-diffusion was studied in alumina single crystals at 1520 to 1750C by using the gas-solid isotope exchange technique. After diffusion annealing, 18O profiles were determined using secondary ion mass spectrometry. The results indicated that 2 diffusion mechanisms were involved: a bulk diffusion mechanism and a sub-boundary one. The bulk diffusion was described by:

D(cm2/s) = 99.6 exp[-626(kJ/mol)/RT]

while the sub-boundary data obeyed

D(cm2/s) = 3 x 1013exp[-877(kJ/mol)/RT]

D.Prot, M.Miloche, C.Monty: Journal de Physique – Colloques, 1990, C1[1], 1027-33