DIFFUSION AND POINT-DEFECTS IN TIO2-X

The self-diffusion of **4**4Ti has been measured both parallel to and perpendicular to the c axis in rutile single crystals by a serial-sectioning technique as a function of temperature (1000-1500 degree C) and oxygen partial pressure (10** minus **1**4-1 atm). The oxygen-partial-pressure dependence of cation self-diffusion indicates that this self-diffusion occurs by an interstitial-type mechanism and that both trivalent interstitial titanium ions may contribute to cation self-diffusion. Model computations are compared with the experimental data on deviation from stoichiometry, electrical conductivity, cation self-diffusion and chemical diffusion in TiO//2// minus //x. These comparisons provide values of the defect concentrations, cation-defect diffusivities, electron mobility and reasonable values of the correlation factor for cation diffusion by the interstitialcy mechanism.