Preferential diffusion of oxygen along grain boundaries in polycrystalline MgO

Abstract

Self‐diffusion coefficient of oxygen in polycrystalline MgO can be represented by D=4.5×10−5exp(−60200/RT)cm2/sec for 80–115 mesh particles and by D=1.3×10−5exp(−60200/RT)cm2/sec for 170–200 mesh particles. These two activation energies are exactly the same, but the magnitude of the diffusion coefficients varied from one sample to another. When D was recalculated by taking a as the grain radius instead of particle radius, all the data points fall on a single solid line expressed by D=4.5×10−7exp(−60200/RT) cm2/sec. It is important to note that this line approximately meets the Arrhenius plot for oxygen diffusion in single‐crystal MgO. Therefore, we conclude that the diffusion of oxygen along the grain boundaries in polycrystalline MgO is considerably faster than diffusion through the bulk.