The defect structure and migration pathways of cations in cubic zirconia were calculated by using 2 computer modeling techniques. One was based upon the Mott-Littleton method, and considered the defects to be embedded in an otherwise perfect crystal. The other was a super-cell approach which permitted finite defect concentrations to be modeled. By using the former approach, the migration pathways for both intrinsic and dopant cations were calculated. Upon assuming a vacancy mechanism, activation energies which ranged from 3.1 to 5.8eV were deduced. A curved pathway was found to be preferred, to a straight pathway, for highly charged dopants. The effect of the stabilizer concentration upon the properties of the system was analyzed by using the super-cell method, and 3 2 3 2 3 and 4 2 4 2 4 super-cells which contained 3 to 40mol% calcia or yttria were constructed. A random distribution of dopant cations and O vacancies was assumed. After relaxation, it was found that the O vacancies were located next to the Zr cations in the CaO-doped system. They remained randomly ordered in the Y2O3-doped system. Cation vacancies were also created and, after relaxation, they were surrounded by an average of 2.7 oxygen vacancies in both CaO-stabilized and Y2O3-stabilized ZrO2.

Computer Modeling of Ion Migration in Zirconia. M.Kilo, R.A.Jackson, G.Borchardt: Philosophical Magazine, 2003, 83[29], 3309-25