Abstract
ABO(3) perovskites display several physical properties determined by the
characteristics of A and B cations. These compounds have cubic structure
at high temperature. Lower symmetry cells that are distorted cubes are
found at low temperature. Defects modify the properties of these
compounds. Under standard conditions oxygen vacancies are produced.
Cation substitution also alters the characteristics of perovskites.
These materials have been studied by Perturbed Angular Correlation (PAC)
spectroscopy and other hyperfine techniques. In this way abundant
information is available to determine charge distributions close to
probes. In the cubic phase perturbations were detected that are produced
by the interaction of probes with defects. To show up these effects we
analyze the quadrupole interaction at Ta-181 in several compounds: ABO(3) with A = Ca, Sr and Ba, BaTi1-xHfxO3 and PbZr1-xTixO3 for 0 less
than or equal to x less than or equal to 1. Three different quadrupole
interactions were found and are interpreted in terms of distinct
probe-oxygen vacancy configurations.
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