Ac conductivity, dielectric losses, permittivity behavior of Ba x Sr1−x Fe0.8Co0.2O3−δ (x = 0, 0.5 and 1) ceramics

In this paper, we have investigated ac conductivity, dielectric losses, permittivity of Ba x Sr1−x Fe0.8Co0.2O3−δ (x = 0, 0.5, 1) ceramics. It has been observed that increase in barium content decreases activation energy (i.e. conductivity increases) in the higher temperature region (550–770 K). In the lower temperature region system with x = 0 shows metallic conductor behavior and system with x = 1 shows thermally activated behavior. The ferroelectric peak temperatures are observed at 700, 750 and 723 K for x = 0, 0.5 and 1, respectively. This peak temperature can be attributed to the oxygen-vacancy-related dielectric relaxation. With the increase of barium content the dielectric dispersion tend to diminishes. Partial substitution of strontium with barium (for x = 0.5) reduces dielectric losses by 50%.