The diffusion of radiotracer S in single crystals and in pressed powder compacts of NiO was studied. The diffusivities for undoped single crystals were described by:

D(cm2/s) = 1.89 x 10-5 exp[-185.3(kJ/mol)/RT]

between 820 and 1200C and under a virtually constant (0.77 to 1atm) oxygen pressure.

D.R.Chang, R.Nemoto, J.B.Wagner: Metallurgical Transactions A, 1976, 7[5], 803-6