Non-ionic contributions to the Electric Field Gradient at 111Cd/181Ta impurities in Bixbyites

M. RENTERIA; K. FREITAG; L. A. ERRICO

HYPERFINE INTERACTIONS

springer

Lugar: Lovaina; Año: 1999 vol. 120 p. 449 - 452

0304-3843

We present results of PAC experiments on 181Hf-implanted Lu- and Sm-sesquioxides. The hyperfine interactions at 181Ta located at both cation sites of the bixbyite structure were characterized, increasing the electric-field gradient (EFG) data at Ta-impurity sites in these systems. The accumulated EFG data with 181Ta enables a first attempt to investigate the universal character of the empirical correlation between local and ionic contributions to the EFG in binary oxides. In the specific case of the bixbyite group, a factorization of EFG as function of the electronic characteristics of the probe, the geometry of the cation coordination with its nearest (NN) and next-near neighbours (NNN), and the lattice parameter of the sesquioxides is proposed. This factorization explains the experimental EFG results at Ta/Cd sites in bixbyites and is in qualitative agreement with a simplified decomposition of the EFG valence contribution coming from ab-initio calculations.