Ion microprobe analysis with a sub-micrometer diameter spot reveals a sharp, 2 μm gradient in oxygen isotope ratio proving that oxygen diffusion in zircon is slow even under prolonged high-grade metamorphism. The data are consistent with an oxygen diffusion coefÞ cient of 10–23.5±1 cm2/s. Furthermore, this gradient is found in a zircon that contains clear textural evidence of recrystallization ...

We discuss oxygen and cation diffusion processes in oxygen ion conductors. While the high oxygen diffusivity determines the proper oxygen ion conductivity, slow cation diffusion processes are important for sintering and degradation processes. In the first part of the paper we discuss an analytical model for the ionic conductivity of a strongly acceptor doped, fluorite-type oxygen ion conductor,...