<i>In situ</i> Profiles of Oxygen Diffusion in SrTiO ₃ : Bulk Behavior and Boundary Effects

Abstract

Diffusion profiles have been recorded in situ and evaluated using an optical technique. In this way, bulk diffusion coefficients have been reliably and quantitatively measured. It is shown that the values agree with calculations without using adjustable parameters if the coupling of the diffusing species to internal redox changes of the dopants is accounted for. Measurements on single crystals and on bicrystals with and without crack formation provide worthwhile information on the influence of free relaxed surfaces, freshly produced (crack) surfaces, and grain boundaries on the surface reaction rate and diffusional process. The inward diffusion of oxygen via crack surfaces is characterized by enhanced diffusion coefficients.