Electric Field Gradients at 181Ta Impurity Site in Yb, Y and Dy Sesquioxides

A.F. PASQUEVICH; A.G. BIBILONI; C.P. MASSOLO; M. RENTERÍA; J.A. VERCESI; K. FREITAG

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

American Physical Society

Lugar: Ridge, NY; Año: 1994 vol. 49 p. 14331 - 14336

0163-1829

The perturbed-angular-correlation (PAC) technique has been applied to the study of the internal electric-field gradients (EFG) in Yb, Y, and Dy sesquioxides. The 181Ta .18PAC probes were introduced in the oxide lattices by means of181Hf implantation, which decays to the Ta impurity by β emission. The tracer 181TaTa181 was used and the results were compared to those obtained in bixbyite structure compounds using 111CdCd111 as a probe. The measured EFG are essentially independent from the probe, reflecting the structure characteristics of both crystalline sites in these compounds. In the case of 181Hf4+Hf4+181 and 181Ta5+Ta5+181, charge compensation (the cations are 3+) seems to be accomplished through a uniform distribution of the probe?s extra electrons in the neighboring oxygen anions. Comparisons of the results to point-charge model predictions are also discussed.