Electric Field Gradient in Binary Oxides at the 111 Cd Impurity Site

R. WEHT; G. FABRICIUS; M. WEISSMANN; M. RENTERÍA; C.P. MASSOLO; A.G. BIBILONI

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 1994 vol. 49 p. 14939 - 14944

1098-0121

The electric-field gradient (EFG) at the probe-atom site in binary oxides has been theoretically estimated, assuming it is composed of two terms. The first term is local, due to deformation of the valence orbitals of the probe atom, and was calculated by methods of quantum chemistry. The second term is due to the rest of the lattice ions, and these were taken as point charges. In this work we found, for the well-known Cd111 probe, a correlation between the local and ionic contributions to the EFG for the 29 oxides studied, which is very similar to the one deduced empirically from time-differential perturbed-angular-correlation experiments. Therefore, the hypothesis used to perform that empirical correlation is confirmed, i.e., both terms have different sign and the absolute value of the local contribution is larger than the ionic one in most cases.