Dielectric response features and oxygen migration on rare earth modified lead titanate ferroelectric ceramics
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Rare earth (RE) and manganese-modified lead titanate ceramics were studied concerning the presence of two peaks in the temperature dependence of the dielectric permittivity. 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 the observed 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 and electrical 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.
KeywordsRare Earth Oxygen Vacancy Dielectric Permittivity Perovskite Structure Thermal Hysteresis
The authors wish to thank the Third World Academy of Sciences (RG/PHYS/LA No. 99-050, No. 02-225, No. 05-043) and FAPESP Brazilian agency (Proc. No. 06/60013-5) for financial support, and ICTP for financial support of Latin-American Network of Ferroelectric Materials (NET-43). Dr. Peláiz-Barranco wishes to thank Universidad Autónoma de Madrid for financial support. Dr. Calderón-Piñar wishes to thank the ICTP program for Training and Research in Italian laboratories.
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