Microscopic mechanism of stability in yttria-doped zirconia

Abstract

The relaxed configurations of yttria-stabilised zirconia (YSZ) between 3 and 10 mol % of Y₂O₃ were modeled using the pseudopotential technique. In the displacive limit of a double-well potential model, the vibrational mode corresponding to the soft phonon in pure c-ZrO₂ was calculated for each Y₂O₃ composition. These anharmonic vibrations, associated with the stabilization of YSZ, were investigated within the self-consistent phonon approximation making obtainable the fine structure in spectral density. In studying the phonon dynamics, we use the displacement probability density, which can quantify very accurately the transition temperature necessary for stabilizing the YSZ cubic phase.