This work determines the self-diffusion coefficients of indium in TiO2 single crystal (rutile). Diffusion concentration profiles were imposed by deposition of a thin surface layer of InCl3 on the TiO2 single crystal and subsequent annealing in the temperature range 1073–1573 K. The diffusion-induced concentration profiles of indium as a function of depth were determined using secondary ion mass spectrometry (SIMS). These diffusion profiles were used to calculate the self-diffusion coefficients of indium in the polycrystalline In2TiO5 surface layer and the TiO2 single crystal. The temperature dependence of the respective diffusion coefficients, in the range 1073–1573 K, can be expressed by the following formulas:
The obtained activation energy for bulk diffusion of indium in rutile (316 kJ/mol) is similar to that of zirconium in rutile (325 kJ/mol). The determined diffusion data can be used in selection of optimal processing conditions for TiO2–In2O3 solid solutions.