Tracer O diffusion coefficients in Ca-doped polycrystalline samples were determined by using a gas-solid exchange technique and secondary ion mass spectrometry. Samples which contained few pores were used, in order to avoid their effect upon the diffusion profiles. The latter were attributed to volume diffusion alone, since no grain boundary diffusion was observed. Depending upon the effect of Ca doping on tracer diffusivity, the Ca contents could be divided into 3 regions. For Ca contents of 0 to 0.17mol%, the tracer diffusivity changed little with Ca doping and exhibited a minimum at 0.02mol%. The tracer diffusivity increased markedly between 0.17 and 0.54mol%, and saturated at 0.54mol% or above; because of a solubility limit. The activation energies for O diffusion were estimated to be equal to 249 to 282kT/mol.

Effect of Calcium Dopant on Oxide Ion Diffusion in Yttria Ceramics. N.Saito, H.Haneda, I.Sakaguchi, T.Ikegami: Journal of Materials Research, 2001, 16[8], 2362-8