Dielectric and piezoelectric properties of Bi0.5Na0.5TiO3–BaNb2O6 lead-free piezoelectric ceramics

Abstract

Lead-free piezoelectric ceramics (1 − x)Bi0.5Na0.5TiO3–xBaNb2O6 (BNT–BN100x), a new member of the BNT-based group, was prepared by conventional solid state reaction. X-ray diffraction showed that BaNb2O6 (BN) diffused into the lattice of Bi0.5Na0.5TiO3 to form a solid solution with perovskite-type structure. The temperature dependence of dielectric constant er 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 BaNb2O6. 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–BN100x ceramics were good candidates for use as lead-free piezoelectric ceramics.