Solute Diffusion of Platinum in Rutile Titanium Dioxide

195Pt solute diffusion coefficients in undoped single-crystal rutile TiO2 have been determined parallel to the c-axis over the temperature range of 1073–1523 K and oxygen partial pressure of 101 kPa. This has yielded the following temperature dependence: D195Pt=1.3±3.2×10−13m2s−1exp(−122.0±13.6kJmol−1RT) On the basis of this result, it has been concluded that 195Pt diffuses via an interstitial mechanism involving rapid transport parallel to the c-axis through open interstitial diffusion channels. While other divalent cations have also displayed diffusion via the same mechanism, and report diffusion rates that greatly exceed that for cation self-diffusion, the overall rate of 195Pt diffusion is slow. This has been attributed to the size of Pt2+ (0.80 A) which is comparative to the dimension of interstitial channels (0.77 A) through which transport is believed to be taking place.

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