Dielectric and impedance studies of (Pb1−xCax)(Fe0.5Nb0.5)O3 dielectric ceramics

Ceramic samples of (Pb1−xCax)(Fe0.5Nb0.5)O3 with x = 0.20, 0.40, 0.45, 0.50, 0.55 and 0.60 were obtained by columbite precursor method. All the synthesized samples have perovskite structure with pseudo-cubic symmetry. Dielectric properties of all the samples were measured as a function of frequency from room temperature up to 573 K. Two dielectric anomalies were observed in εr–T plots at about 400 and 500 K. The impedance analysis depicts a single relaxation process. Activation energies obtained from temperature dependence of relaxation frequency, f0 and grain resistance, Rg were found to be more or less comparable. The observed relaxation in all the samples seems to be due to electron relaxation associated with oxygen vacancies.