Low-temperature dielectric and impedance properties of Ba1-xSrxTiO3 and BaTi1-xTaxO3 ceramics

In this work, two series of BaTiO3-based ceramics, Ba1-xSrxTiO3 (x = 0, 0.2, 0.4, 0.6, 0.8) and BaTi1-xTaxO3 (x = 0.03, 0.06, 0.075, 0.09, 0.1), were synthesized by using standard solid-state reaction method at 1350 ?C, and then sintered at 1400 ?C for 10 h in air. Frequency-dependent dielectric and impedance properties were investigated at low temperature range of 100-300K. The changes in dielectric properties of the Ba1-xSrxTiO3 ceramics are believed to originate from the phase transition due to the different A-site Sr2+ doping concentration. The local electron-pinned defect-dipole effect is responsible for the enhancement of dielectric constant observed in the B-site Ta5+ doped BaTi1-xTaxO3 ceramics. The complex impedance analysis was used to discern the temperature and frequency dependence of grains and grain boundaries responses. The results suggest that A- and B-site doped BaTiO3 ceramics can be applied for different dielectric devices at low temperatures.