The diffusivity of erbium in the anatase phase of titanium dioxide (TiO2) has been studied for various temperatures ranging from 800 degrees C to 1, 000 degrees C. Samples of TiO2, with a 10 nm thick buried layer containing 0.5 at% erbium, were fabricated by radio-frequency magnetron sputtering and subsequently heat treated. The erbium concentration profiles were measured by secondary ion mass spectrometry, allowing for determination of the temperature-dependent diffusion coefficients. These were found to follow an Arrhenius law with an activation energy of (2.1 +/- 0.2) eV. X-ray diffraction revealed that the TiO2 films consisted of polycrystalline grains of size approximate to 100 nm. (C) 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).