Using tracer and sectioning techniques, the migration of divalent and trivalent cations was investigated at temperatures of between about 500 and 750C; under conditions of heterodiffusion at infinite dilution. This was achieved by allowing radiotracers with a high specific activity to diffuse in the intrinsic range of high-purity single crystals. The Fe3+, whose diffusion had been considered to be impossible, gave good diffusion profiles when experimental precautions were taken. The diffusivity of 59Fe at 717C was estimated to be 1.10 x 10-8cm2/s.

Diffusion of Heterovalent Ions in Ionic Crystals. F.Bénière, K.V.Reddy: Journal of Physics and Chemistry of Solids, 1986, 47[1], 69-77