Dielectric relaxation in Pb(Fe2/3W1/3)O-3 ceramics

Lead iron tungstate, Pb(Fe2/3W1/3)O-3. (PFW), exhibits typical ferroelectri c relaxer characteristics around 185K (10kHz). Besides the ferroelectric re laxation, a second dielectric relaxation was observed in undoped, La3+ and Mn2+ doped PFW ceramics in the temperature range of 200-350K. The intensity of dielectric permittivity and loss factor peaks was found to be strongly related to the resistivity: it increases with the increase in the resistivi ty. The relaxation activation energy is also in the same range of the condu tion activation energy for each sample. The relaxation mechanism is discuss ed and a space charge polarization is suggested to explain the observed die lectric relaxation.