Piezoelectric and dielectric properties of CeO_2-doped Bi_(0.5)Na_(0.44)K_(0.06)TiO_3 lead-free ceramics

摘要

CeO_2-doped lead-free Bi_(0.5)Na_(0.44)K_(0.06)TiO_3piezoelectric ceramics (0-1.0 wt percent) were synthesized by conventional ceramics technique. X-ray diffraction shows that CeO_2 diffuses into the lattice of Bi_(0.5)Na_(0.44)K_(0.06)TiO_3 to form a solid solution, but does not change the rhombohedral phase in Bi_(0.5)Na_(0.44)K_(0.06)TiO_3 during sintering. The temperature dependence of dielectric constant epsilon_r and dielectric loss tan S 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 percent CeO_2shows 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 percent.