The diffusion of Ni was measured in Co1-xO, under O partial pressures of 0.21 and 1.5 x 10-5atm at 1000 to 1600C. A thin film of NiO was deposited onto the surface of CoO single crystals by means of radio-frequency sputtering. Concentration-penetration curves were then obtained by electron-beam micro-analysis and secondary ion mass spectrometry. The results could be described by:

D (cm2/s) = 2.78 x 10-2 exp[-2.02(eV)/kT]

for PO2 = 0.21atm, and by:

D (cm2/s) = 1.22 x 10-2 exp[-2.15(eV)/kT]

for PO2 = 1.5 x 10-5atm. The PO2 exponent was smaller for impurity diffusion than for self-diffusion. This was interpreted as being evidence of an interaction between Ni atoms and doubly-charged vacancies.

Impurity Diffusion of Ni in Co1-xO Single Crystals. R.Gomri, H.Boussetta, C.Bahezre, C.Monty: Solid State Ionics, 1984, 12, 227-33