The self-diffusivity of O in monocrystals was studied as a function of the O pressure, at 1100C, by using the gas-solid isotope exchange method. Diffusion annealing was carried out in H2-18H2O atmospheres, and the resultant 18O diffusion profiles were measured by means of secondary ion mass spectrometry. The diffusion coefficients were calculated by using a solution of Fick's second law which took account of evaporation and exchange at the surface. The results (table 58) showed that O diffusion coefficients at 1100C did not depend upon the O pressure, and the values were smaller than published ones. A comparison with previous data on Cr self-diffusion in the same monocrystals revealed that O diffusion was faster than Cr diffusion.

A.C.S.Sabioni, A.M.Huntz, F.Millot, C.Monty: Philosophical Magazine A, 1992, 66[3], 351-60

Table 56

Bulk Diffusion (PO2 = 10-4atm) of Fe

in a Cr2O3 Film on Ni70Cr30