High-field/high-frequency EPR of paramagnetic functional centers in Cu2+- and Fe3+-modified polycrystalline Pb[ZrxTi1-x]O-3 ferroelectrics

Copper(II)- and iron(III)-modified Pb[ZrxTi1-x]O-3 ferroelectrics were
investigated by means of highfield/high-frequency EPR. The results
obtained suggest that CU2+ and Fe3+ both substitute as acceptor centers
for [ZrTi](4+). Whereas for the iron-doped system the charge
compensating oxygen vacancies (VO) lead to the formation of charged
(Fe'(Ti)- VO) defect associates, no such associates have been observed
for the copper-modified system. As regards the morphotropic phase
boundary, the model of a mesoscopic mixing of the pure-member phases
has been refined to a picture in which a nanoscale composition
distribution prevails.