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:
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 Å) which is comparative to the dimension of interstitial channels (0.77 Å) through which transport is believed to be taking place.