Defect ordering in aliovalently doped cubic zirconia from first principles- art. no. 014106

Defect ordering in aliovalently doped cubic-stabilized zirconia is studied using gradient corrected density-functional calculations. Intra- and inters ublattice ordering interactions are investigated for both cation (Zr and do pant ions) and anion (oxygen ions and vacancies) species; For yttria-stabil ized zirconia, the crystal structure of the experimentally identified, orde red compound delta -Zr3Y4O12 is established, and we predict metastable zirc onia-rich ordered phases. Anion vacancies repel each other at short separat ions, but show an energetic tendency to align as third-nearest neighbors al ong (111) directions. Calculations with divalent (Be, Mg, Ca, Sr, Ba) and t rivalent (Y, Sc, B, Al, Ga, In) oxides show that anion vacancies prefer to be close to the smaller of the cations (Zr or dopant ion). When the dopant cation is close in size to Zr, the vacancies show no particular preference, and are thus less prone to be bound preferentially to any particular catio n type when the vacancies traverse such oxides. This ordering tendency offe rs insight into the observed high conductivity of Y2O3- and Sc2O3-stabilize d zirconia, as well as recent results using, e.g., lanthanide oxides. The c alculations point to In2O3 as a particularly promising stabilizer for high ionic conductivity. Thus we are able to directly link (thermodynamic) defec t ordering to (kinetic) ionic conductivity in cubic-stabilized zirconia usi ng first-principles atomistic calculations.