Microstructure and electrical properties of La2O3-doped Bi0.5(Na0.68K0.22Li0.1)0.5TiO3 lead-free piezoelectric ceramics

La2O3-doped Bi0.5(Na0.68K0.22Li0.1)0.5TiO3 lead-free piezoelectric ceramics have been successfully prepared by conventional solid state method and the effects of La2O3 doping on microstructure and electrical properties of the ceramics were investigated. The X-ray diffraction patterns demonstrated all ceramics possessed pure perovskite structure with rhombohedral symmetry. The temperature dependence of dielectric constant and dielectric loss revealed two abnormal dielectric peaks of Td and Tm, which implied that from room temperature to 500 °C all ceramics underwent two phase transitions which were from ferroelectric to anti-ferroelectric and anti-ferroelectric to paraelectric, respectively. It was also found that the transition temperature Td decreased with the addition of La2O3. Diffuse phase transition and frequency dispersion of the dielectric constant were observed in all ceramics. Dielectric relaxor behavior obeyed the modified Curie–Weiss law. The results revealed that all samples had relaxor characteristics. In addition, for the ceramics with 0.1 wt.% La2O3, optimized electrical properties were obtained, which were as follows: ɛr = 1254 (1 kHz), tan δ = 0.0483, d33 = 192 pC/N, Kp = 0.27, Pr = 29.1 μC/cm2, and Ec = 29.0 kV/cm.