Theoretical calculations on the Electric Field Gradient in HfO2:Cd and ZrO2:Cd.

M. A. TAYLOR; L. A. ERRICO; R. E. ALONSO

Ginebra, Suiza

Conferencia; 3rd Joint International Conference on Hyperfine Interactions & International Symposium on Nuclear Quadrupole Interaction; 2010

CERN

Trabajo presentado en forma de poster durante la conferencia. Zirconia-based materials and HfO2 are in the focus of interest for many years due to their outstanding electrical and mechanical properties. HfO2 and ZrO2 are very similar in their crystallographic and electronic structure. They have three polymorphs at atmospheric pressure: their low-temperature phase is monoclinic, increasing the temperature they transform to a tetragonal phase, and finally to a cubic phase as temperature increases. HfO2 and ZrO2 were largely studied with the Perturbed Angular Correlations (PAC) technique with the 181Hf→181Ta probe. But a reliable model for the electric field gradient were present recently for Ta-doped HfO2 [1].  PAC experiments with the 111In→111Cd were less common, and as far as we know, only two works were reported in the literature [2, 3].  In this work, we analyze the EFG at the Cd site for the doped monoclinic structure of ZrO2 and HfO2. The theoretical results are compared with those determined experimentally by means of PAC spectroscopy. Our calculations are based on the Density Functional Theory (DFT), with the Local Density approximation (LDA) and the Generalized Gradient Approximation (GGA) for the exchange correlation potential, as implemented in the WIEN2k version of the Full Potential APW+LO. Different charge states for the Cd impurity are analyzed, and their influence on the hyperfine parameters is discussed.