Synthesis, dielectric and impedance spectroscopy study of temperature stable Ta₂O₅ modified 0.85BaTiO₃-0.15Bi(Mg_0.5Ti_0.5)O₃ ceramics

In the present study, 0.85BaTiO₃–0.15Bi(Mg_0.5Ti_0.5)O₃-xTa₂O₅ (x = 0, 0.01, 0.015, 0.02, 0.025) processed via the conventional mix oxide route. The phase, microstructure, and dielectric properties were studied. Single perovskite phase developed and studied via XRD. A Dense microstructure for each composition was developed with the pseudo-crystal structure. Low grain size <3 μm is achieved for each composition. A high dielectric constant (ε_r) > 1000 and low dielectric loss (tanδ <2.5 %) is obtained for x ≤ 0.020, with high stability over a broad range of temperatures (<0 °C to 180 °C). These compositions are considered to be suitable for designing X9R capacitors. In complex impedance analysis, the decreasing value of the bulk impedance upon increasing the temperature revealed the negative temperature coefficient of resistance (NTCR) behavior. The small conductivity and high activation energy value for x = 0.01 demonstrate the temperature stability of this ceramic.