Structural and electrical aspects of microwave sintered (Ba_1-xCa_xSn_0.09 Ti_0.91) O₃ ceramics

Barium titanate ceramics with A- site and B-site substitutions are intriguing alternative to lead-based Pb (Zr, Ti) O₃ (PZT) because of its comparable properties to soft-PZTs. In this paper, (Ba_xCa_1-xSn_0.09 Ti_0.91) O₃ (x = 0.0525, 0.0575, 0.060) ceramics are prepared using a solid-state reaction technique followed by microwave sintering at 1350 °C for 30 minutes. Structural and electrical properties are investigated. X -ray diffraction shows that the compositions exhibit a tetragonal crystal structure having P4mm symmetry. Temperature dependent dielectric constant measurements in the temperature range of 25 °C to 120 °C shows high dielectric constant of 26250 at 40kHz for BCST ceramics with x=0.0525 and the Curie temperature T_c increases with Ca concentration. The results of dielectric measurements as a function of frequency are also reported. The dielectric loss (tan δ) values in the temperature range 25 °C to 120 °C are observed to be less than 0.03, for all BCST ceramics. The AC conductivity, impedance spectroscopy studies and the conduction mechanism on the basis of Arrhenius plot are discussed in the above-mentioned temperature range.