Relaxation motion and possible memory of domain structures in barium titanate ceramics studied by mechanical and dielectric losses
Résumé
The relaxation motion and memory effect of domain structures have been investigated using mechanical and dielectric loss measurements in BaTiO3 ceramics with grains sizes varied from 1 mgrm to 50 mgrm. The measurements of mechanical loss, elastic modulus, dielectric loss and permittivity show that each phase transition induces a loss peak and an anomaly in the dielectric constants and elastic modulus, furthermore, a number of relaxation loss peaks due to ferroelectric domains in the samples with large grain have been observed. All the relaxation peaks can be analysed by Arrhenius relationship for a wide range of frequency from 10–2 to 106 Hz. The activation energies of relaxation peaks have been determined as 0.92 eV, 0.68 eV, 0.47 eV, and 0.29 eV for the peaks located in the tetragonal, orthorhombic, and rhombohedral phase, with Arrhenius perfactor in the order of 10–13 s. Moreover, one relaxation process is insensitive to ferroelectric phase transitions, and it can exist in all the ferroelectric phases...