Oxygen vacancies in tetragonal ZrO_2: ab initio embedded cluster calculations

摘要

Formation of oxygen vacancies in bulk tetragonal ZrO_2 and at its (101) and (001) surfaces was studied using ab initio embedded cluster calculations. A new technique was proposed for generating a set of point charges that represents the Coulomb field of the crystal environment both for bulk and surface cluster structures. This technique provides the rapid convergence of the calculated Madelung potential to the unique true value. The estimated bulk vacancy formation energy in tetragonal ZrO_2 is 8.8 eV, while surface vacancy energy formation depends on the type of the surface and position of removed oxygen atom and varies from 8.3 to 9.3 eV. The calculated activation energy of oxygen vacancy migration in bulk ZrO_2 is 1.95 eV.