Dielectric Properties of Pb(Fe_2/3W_1/3)_1−xMn_xO₃ Ceramics in the Temperature Range 200–600 K

Abstract

The dielectric properties of Mn-doped Pb(Fe_2/3W_1/3)_1−xMn_xO₃ (x = 0, 0.001, 0.003, and 0.005) in the temperature range 200–600 K were investigated. Two sets of dielectric peaks, located at 200–350 K and 350–600 K, were observed. The intensity of the dielectric permittivity and loss factor peaks for both relaxations decreased with the increase in the Mn content and no peak occurred when x = 0.005. Nonlinear current–voltage (I–V) behavior was observed in the samples containing less than 0.005Mn. The activation energy values for the relaxations at 200–350 K and at 350–600 K were around 0.42 and 0.56 eV, respectively. The direct current conduction activation energies were around 0.41 eV. Nitrogen annealing eliminated the relaxation peaks at 200–350 K while oxygen annealing enhanced them. Both annealings eliminated the dielectric peaks at 350–600 K. The nonlinear I–V characteristic tended to vanish either after the oxygen or the nitrogen annealing treatments. Relaxation mechanisms are proposed and discussed. It is suggested that the relaxation at 200–350 K is related to electron hole while the relaxation at 350–600 K is attributed to microstructure-dependent space-charge polarization.