Diffusion in MgO (Magnesia or periclase)

Abstract

MgO is an ionically bounded ceramics with extremely high melting point of ~2852 °C. It has excellent insulating properties with high temperature stability. MgO single crystal is a commonly used substrate for preparing ferroelectric thin films because of its low dielectric constant. It has been considered a potential insulating material for high-temperature applications in corrosive environments and, therefore, the effects of electric fields are of great interest. Among other influences electric field may enhance mas transport in MgO and thus shorten the useful life of this oxide at high temperature. The use of MgO as a high temperature insulator might have been one of the reasons for the extensive diffusion studies in this ceramics—more so than in other ceramics—including self-diffusion of the Mg cation, O anion and a wide variety of impurity diffusion. The melting point of MgO is an indication of a deep potential well and for the escape of the diffusant (self or impurity) a sufficient thermal energy is required. The depth, width and asymmetry of the well on the potential energy curve is associated with atomic transport and the ease of diffusion in this system. Diffusion data (self, solute, grain boundary and dislocation) are compiled at the end of the chapter.