Dielectric and piezoelectric properties of Bi_(0.5)Na_(0.5)TiO_3-BaNb_2O_6 lead-free piezoelectric ceramics

摘要

Lead-free piezoelectric ceramics (l-x)Bi_(0.5)-Na_(0.5)TiO_(3-x)BaNb_2O_6 (BNT-BN10x), a new member of the BNT-based group, was prepared by conventional solid state reaction. X-ray diffraction showed that BaNb_2O_6 (BN) diffused into the lattice of Bi_(0.5)Na_(0.5)TiO_3 to form a solid solution with perovskite-type structure. The temperature dependence of dielectric constant ε_τ revealed that the solid solution underwent two phase transitions from ferroelectric to anti-ferroelectric and anti-ferroelectric to paraelectric. Both the transition temperature T_d and T_m were shifted to lower with the increasing content of BaN-b_2O_6. The temperature dependence of dielectric constant at different frequency revealed that the solid solution exhibited obviously dielectric relaxation characteristics. The sample with x = 0.6 mol% exhibited excellent electrical properties, piezoelectric constant d_(33) = 94 pC/N; electromechanical coupling factor k_p - 0.185. The results showed that BNT-BN1OOx ceramics were good candidates for use as lead-free piezoelectric ceramics.