Piezoelectric and dielectric properties of CeO2-doped Bi0.5Na0.44K0.06TiO3 lead-free ceramics

CeO2-doped lead-free Bi0.5Na0.44K0.06TiO3 piezoelectric ceramics (0–1.0 wt%) were synthesized by conventional ceramics technique. X-ray diffraction shows that CeO2 diffuses into the lattice of Bi0.5Na0.44K0.06TiO3 to form a solid solution, but does not change the rhombohedral phase in Bi0.5Na0.44K0.06TiO3 during sintering. The temperature dependence of dielectric constant ɛr and dielectric loss tan δ measurement reveals that the solid solutions experience two phase transitions from ferroelectric to anti-ferroelectric and anti-ferroelectric to paraelectric, which can be proved by P–E hysteresis loops at different temperatures. The specimen containing 0.2 wt% CeO2 shows that the coercive field Ec decreases from 8.22 to 4.76 kV/mm while the remnant polarization Pr decreases from 37.2 to 30.0 μC/cm2, corresponding to the enhancement of piezoelectric constant d33 of 132 pC/N and electromechanical coupling factor kp of 27.8%.