Oxygen diffusion coefficients were measured in polycrystalline ZnO by means of the gas-solid exchange method using the isotope 18O as the tracer. The diffusion annealing was performed at 892 and 992C, in an Ar+18O2 atmosphere under oxygen partial pressures of 0.1 to 1atm. After diffusion annealing, the 18O diffusion profiles were determined using secondary ion mass spectrometry. Increasing the oxygen pressure led to an increase in the oxygen diffusion in ZnO. The bulk diffusion coefficients depended upon oxygen pressure according to D α (PO2)0.5, at 882C, or D α (PO2)0.4 at 992C, which indicated that the oxygen bulk diffusion mechanism should preferentially take place by means of interstitial oxygen having a null effective charge. The grain boundary diffusion coefficients showed little dependence upon oxygen pressure at 882C, given by D α (PO2)0.2, which should correspond to a diffusion mechanism by means of interstitial oxygen, with a double negative charge, but at 992C this dependence was D α (PO2)0.5 corresponding to a diffusion mechanism by interstitial oxygen having a null effective charge. The results also showed that the grain boundary was a fast path for oxygen diffusion in polycrystalline ZnO.

Study of Oxygen Diffusion in Polycrystalline ZnO by SIMS. Sabioni, A.C.S., Daniel, A.M.J.M., Huntz, A.M., Ferraz, W.B., Jomard, F.: Defect and Diffusion Forum, 2009, 289-292, 523-30