Preparation and electrical properties of Al and Te co-doped BNT-BKT ceramics

0.8Bi0.5Na0.5TiO3(BNT)-0.2Bi0.5K0.5TiO3(BKT) ceramics co-doped with Al2O3 and TeO2 (BNT-BKT-xAT) were prepared using conventional solid-state-reaction method. X-ray diffraction (XRD) analysis of samples with doping concentrations x <= 0.10 confirmed a pure perovskite phase, with relative densities over 95%. The sample with x = 0.05 exhibited better dielectric, ferroelectric and piezoelectric performances, i.e., a dielectric constant of 4900 at 1 kHz, a coercive electric field (Ec) of 42.8 kV/cm, remanent polarization (Pr) of 31.8 mu C/cm2, saturation polarization (Ps) of 45.8 mu C/cm2, and a piezoelectric coefficient (d33) of 160 pC/N. Increasing the doping concentration resulted in a rise in the phase transition temperature. Moreover, at a higher doping level (x = 0.16), the samples exhibited semiconducting behavior, i.e., a temperature-dependent electrical resistivity. These findings indicate that such Al/Te co-doped BNT-BNT ceramics, particularly with x = 0.05 and x = 0.16, are promising candidates for piezoelectric and temperature sensing applications.