Ceramics-Silikáty 16, (2) 113 - 123 (1972)

The method for measuring the oxygen self-diffusion coefficient D is based on 160 and 180 heterogeneous isotopic exchange between the gaseous and the solid phase. The determination proper of D has two variants, i.e. mass spectrometric analysis of the gaseous samples or proton activation of a solid sample. An apparatus for isotopic exchange in both variants was developed. Suitability of mass spectrometric evaluation especially for polycrystalline substances was proved by experiments with TiO₂ and BaTiO₃ monocrystals and with polycrystalline titanate substances. The proton activation method is applicable for quantitative measurement and provides results identical with those of mass spectrometry. Oxygen self-diffusion coefficients were measured for BaTiO₃, CaTiO₃ and Fe- and Na-doped CaTiO₃. The activation energy of self-diffusion in polycrystalline BaTiO₃ was deterrnined from the temperature dependence of D.