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 epsilon(r) and dielectric loss tan delta 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 E-c decreases from 8.22 to 4.76 kV/mm while the remnant polarization P-r decreases from 37.2 to 30.0 mu C/cm(2), corresponding to the enhancement of piezoelectric constant d(33) of 132 pC/N and electromechanical coupling factor k(p) of 27.8%. (c) 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved.