Grain boundary mobility in Y2O3: Defect mechanism and dopant effects

The effects of the dopants, Mg2+, Sr2+, Sc3+, Yb3+, Gd3+, La3+, Ti4+, Zr4+, Ce4+, and Nb5+, On the grain boundary mobility of dense Y2O3 have been investigated from 1500 degrees to 1650 degrees C, Parabolic grain growth has been observed in all cases over a grain size from 0.31 to 12.5 mu m, Together with atmospheric effects, the results suggest that interstitial transport is the rate-limiting step for diffusive processes in Y2O3, which is also the case in CeO2, The effect of solute drag cannot be ascertained but the anomalous effect of undersized dopants (Ti and Nb) on diffusion enhancement, previously reported in CeO2, is again confirmed, Indications of very large binding energies between aliovalent dopants and oxygen defects are also observed, Overall, the most effective grain growth inhibitor is Zr4+, while the most potent grain growth promoter is Sr2+, both at 1.0% concentration.