Effect of the calcium dopant on oxide ion diffusion in yttria ceramics

Abstract

Tracer oxygen diffusion coefficients, D*, in polycrystalline yttria doped with Ca have been determined by a gas–solid exchange technique and secondary ion mass spectrometry. Samples containing few pores were used to avoid their influences on diffusion profiles. The resulting profiles were assigned only to volume diffusion; no grain boundary diffusion was observed. According to the effects of Ca doping on D*, the Ca contents are divided into three regions. In a Ca content region of 0–0.17 mol%, D* changed a little with Ca doping and took a minimum experimentally at 0.02 mol%. D* increased significantly within a range of 0.17–0.54 mol% and saturated at 0.54 mol% or above because of a solubility limit. The activation energies of oxygen diffusion were estimated at 249–282 kJ/mol.