Effect of A- and B-site doping on the low-temperature dielectric and impedance properties of BaTiO3-based 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. Frequency-dependent dielectric and impedance properties were investigated in low temperature range of 300-100 K. The changes in dielectric properties of Ba1-xSrxTiO3 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 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 the application of A- and B-site doped BaTiO3 ceramics in the field of dielectric devices at low temperatures.