Isothermal relaxation of field-biased barium stannate titanate

The isothermal time dependences of the dielectric constant and the discharging current of barium stannate titanate ceramics after application or removal of a step field were investigated in both ferroelectric and paraelectric temperature regions. The experimental results exhibited a substantial difference for these two phases. For the ferroelectric phase, the relaxation of the dielectric constant is weak and the discharging current obeys Hammon's model. While for the paraelectric phase, the relaxation is relatively strong and the discharging current obeys the complex exponential decay model. The relaxation of the field-induced piezoelectric resonance indicated the first relaxation observed in a paraelectric phase sample corresponding to homocharges. The authors proposed that the transportation of homocharges is the microscopic origin of the strong relaxation observed in the paraelectric phase.