Oxygen defects and low-frequency mechanical relaxation in Pb-Ca and Pb-Sm titanates

摘要: The low-frequency behaviour of the isotropic elastic modulus and mechanical loss tangent modified lead titanate ferro-piezoelectric ceramics have been studied by three-point bending technique. Measurements these parameters as a function temperature were performed in frequency range 0.2 to 20 Hz. results show anomalies both at transition below this temperature. wide maxima whose temperatures increase when measuring increases. Values for activation energies obtained that suggest existence relaxation mechanisms where point defects ferroelectric domains are involved. main species should be oxygen vacancies. Comparisons between experimental existing theoretical models made.