Influence of MnO2 and Co3O4 dopants on dielectric properties of Pb(Fe2/3W1/3)O3 ceramics

Dielectric properties of Pb(Fe2/3W1/3)O3 ceramic doped with 0.05-1 mol% of MnO2 or Co3O4 were investigated in a wide temperature range from −160 to 450 °C at frequencies 10 Hz-1 MHz. Besides the maxima corresponding to the ferroelectric-paraelectric transition, at higher temperatures other peaks in temperature dependencies of relative electrical permittivity and dissipation factor were observed, attributed to dielectric relaxation. The location and height of these peaks are strongly related to frequency and the dopant level. Both MnO2 and Co3O4 addition caused a significant increase in the resistivity of PFW ceramic-from 106 Ω cm for undoped samples to 1011 Ω cm for those with 1 mol% of a dopant. The activation energies of relaxation calculated on the basis of dielectric measurements are very close to the conduction activation energies determined in similar temperature range.