Oxygen tracer diffusion in magnesium-doped ZnO ceramics

ZnO samples added with MgO of 1.4-11.7 mol % were used for studying oxygen diffusion by the vapor-solid exchange method. The analyses of oxygen diffusion profiles and impurities were performed by secondary-ion mass spectrometry (SIMS). The results indicate that the increase of MgO concentration enhances oxygen diffusion. The difference between the bulk-diffusion coefficients of oxygen for ZnO samples added with MgO of 1.4 and 11.7 mol % was about two orders of magnitude. It was found that the grain boundary diffusion coefficients of oxygen in ZnO with 11.7 mol % of MgO were larger than those in other samples, by a factor of about 10. Above results indicate that MgO addition into ZnO increases the concentration of effective defects for that promote oxygen diffusion. As the effective defects, the possibilities of vacancy and interstitial of oxygen are discussed. (C) 2010 The Ceramic Society of Japan. All rights reserved.