Oxygen vacancies related electrical response in modified lead titanate ceramics

The electrical conductivity in modified lead titanate is studied around an anomalous behavior, which is observed in the temperature dependence of the dielectric permittivity ( ε ′ ). A peak in ε ′ is obtained around 698 K, which is a temperature higher than that of the ferroelectric–paraelectric transition temperature. The results suggest that the oxygen vacancies are mainly responsible for the conduction behavior in the system. Below 698 K, the relaxation processes are associated to the distorted ionic dipoles by the oxygen vacancies. Above 698 K, the relaxation is associated to the decay of the polarization in the oxygen defect-related dipoles due to their hopping conduction.