Influence of thermal history on relaxation process in barium titanate ceramics

The mechanical and dielectric properties of barium titanate ceramics with different thermal histories (such as cooling, heating and aging) were investigated in temperature range −10 °C to 140 °C at various frequencies. Experimental results clearly showed that in the tetragonal phase, the relaxation processes displayed completely different behaviors depending on the sampleʹs thermal history. A similarity of the thermal history effect on the mechanical and dielectric relaxation behavior was observed, where the oxygen vacancy symmetry and the domain wall mobility played an important role. It was proposed that dielectric relaxation of the aged sample was associated with the reorientation of the dipoles due to the relaxation of oxygen vacancies at A and B sites. The obtained results may provide a helpful guidance for improving the dielectric performance of ferroelectric aged capacitors after a long working time.