Dielectric response features and oxygen migration on rare earth modified lead titanate ferroelectric ceramics

Rare earth (RE) and manganese-modified lead titanate ceramics were studied concerning the presence of two peaks in the temperature dependence of the dielectricpermittivity. An eventual incorporation of the RE into A-site and/or B-site in the perovskite structure and the oxygen migration were considered as causes of theobserved phenomenon. The structural analysis showed that at least a small amount of Ti4? could be substituted by the RE ions. It was considered from the pyroelectric andelectrical conductivity results that, even when an eventual incorporation of the RE into the A-site and/or B-site of the structure could be possible, both peaks could not be associated with paraelectric–ferroelectric (PE-FE) phase transitions. The observed peak at lower temperatures has been associated with the PE-FE phase transitions, whereas the hopping of oxygen vacancies has been considered as the cause for the dielectric anomaly observed at higher temperatures.