Using Blume's stochastic model and the approach of Winkler and Gerdau, we have computed time-dependent effects on perturbed angular correlation (PAC) spectra due to defect motion in solids in the case of I=5/2 electric quadrupole interactions. We report detailed analysis for a family of simple models: "XYZ+Z" models, in which the symmetry axis of an axial EFG is allowed to fluctuate among orientations along x, y, and z axes, and a static axial EFG oriented along the z axis is added to the fluctuating EFGs. When the static EFG is zero, this model is termed the "XYZ" model. Approximate forms are given for G2(t) in the slow and rapid fluctuation regimes, i.e. suitable for the low and high temperature regions, respectively. Where they adequately reflect the underlying physical processes, these expressions allow one to fit PAC data for a wide range of temperatures and dopant concentrations to a single model, thus increasing the uniqueness of the interpretation of the defect properties. Application of the models is illustrated with data from a PAC study of tetragonal zirconia.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Nuclear and High Energy Physics
- Condensed Matter Physics
- Physical and Theoretical Chemistry