Studies on diffuse phase transition in Co- and La-doped BaTi0.85Sn0.15O3

Polycrystalline samples of (Ba1−xLax)(Ti0.85−xCoxSn0.15)O3 (x = 0.00, 0.01, 0.03 and 0.05) with equivalent substitution of La3+ at the place of Ba2+ and Co3+ at the place of Ti4+ were synthesized by the conventional solid-state ceramic route. The prepared samples were characterized by the X-ray diffraction technique for crystal structure. Samples with x ≤ 0.03 were found to have cubic structure at room temperature. Almost no change is found in the lattice parameters due to simultaneous doping of La and Co at A and B sites, respectively. Scanning electron micrographs showed that the grain size was in the range of 2–4 μm. A broad peak in dielectric permittivity vs. temperature plot was observed, indicating a diffuse phase transition in these materials. Dielectric measurements depicted an increase in the broadness of the transition peak and its shifting toward lower temperatures with increasing co-doping of La and Co. Samples with x = 0.01 showed high permittivity ~ 4720 at room temperature and very low dielectric loss ~ 0.009 in the temperature range of 280–330 K at 1 kHz. Hysteresis loop measurements done at room temperature indicated a decrease in remanence due to doping.