Point defects in yttria-stabilized zirconia

The densification that occurs during sintering of certain ceramics has been observed to occur more rapidly and at lower temperatures when a weak external electric field is applied.$^1$ We compute the formation energies of point defects in yttria-stabilized zirconia using first principles density functional theory. We examine interstitials, vacancies, and vacancy complexes including Schottky defects in a Y$_2$Zr$_{14}$O$_{31}$ computational cell, which corresponds to approximately 7 mol\% yttria stabilized zirconia. We relate our results to recent experimental work on electric-field-assisted sintering in yttria-stabilized zirconia, showing how how the expansion of lattice constants observed in diffraction measurements results from increasing defect densities. ~ 1. Raj, R., Cologna, M., and Francis, J. S.~C. Influence of Externally Imposed and Internally Generated Electrical Fields on Grain Growth, Diffusional Creep, Sintering and Related Phenomena in Ceramics. {\em Journal of the American Ceramic Society}{ \bf 94}, 1941 (2011).