Domain walls motions in barium titanate ceramics

The shear modulus and mechanical loss at low frequencies (0.01, 0.3, 1 Hz) are measured by an inverted pendulum for BaTiO3 ceramic with large grain sizes. The permittivity and dielectric losses are also investigated for the same material at higher frequencies between 1 and 100 kHz as function of temperature. Those results show several relaxation peaks in the ferroelectric phases. The activation energy of each peak is obtained to be 0.29, 0.45, 0.68, 0.92 eV. The influences of strain amplitude and thermal treatments are studied specially for the mechanical relaxation peak located in the tetragonal phase. All the relaxation peaks could be associated to the interaction of oxygen vacancies in the domain with different configurations of domain walls by piezoelectric effect. The experimental results show there is one peak occurring in all the three ferroelectric phases, which could mean that the ferroelectric domain structures have certain memory effect.