Dielectric behaviors of Nb2O5–Co2O3 doped BaTiO3–Bi(Mg1/2Ti1/2)O3 ceramics

Nb2O5 and Nb–Co doped 0.85BaTiO3–0.15Bi(Mg1/2Ti1/2)O3 (0.85BT–0.15BMT) ceramics were investigated. From XRD patterns, undesired phase was observed when the (Nb2O5/Nb-Co) doping levels exceed 3 wt.%/2 wt.%, giving rise to the deteriorate dielectric constant. The 0.85BT–0.15BMT ceramics doped with 2 wt.%Nb2O5 was found to possess a moderate dielectric constant (ɛ ∼ 1000) and low dielectric loss (tan δ = 0.9%) at room temperature and 1 kHz, showing flat dielectric behavior over the temperature range from −55 to 155 °C. It was found that the formation of core–shell structure in the BT based ceramics is controlled by the doping sequence of Nb- and Bi-oxides.