Lattice parameters of yttria-doped ceria solid electrolytes

Ceria-rare earth solid solutions are known as solid electrolytes with potential applications in oxygen sensors and solid oxide fuel cells. Trivalent rare earth ions enter into solid solution introducing anion vacancies for charge compensation. These oxygen vacancies are quite mobile at moderate temperatures giving rise to a comparatively high ionic conduction. In this study ceria-u mol% yttria solid solutions were prepared by solid state reactions with u ranging from 0 to 12. These solid solutions exhibit a fluorite-type structure with composition-dependent lattice parameters. The variation of the lattice parameter was studied and correlated with existing empirical equations and with an equation based on the ion-packing model. The effect of an effective ionic radius of Y3+ in eightfold coordination is also discussed.