Dielectric properties and relaxation of Bi0.5Na 0.5TiO3-BaNb2O6 lead-free ceramics

Abstract

A new member of lead-free piezoelectric ceramics of the BNT-based group, (1 - x)Bio-0.5Na0.5TiO3-x BaNb2O 6, was prepared by conventional solid state reaction and its dielectric properties and relaxation was investigated. X-ray diffraction showed that BaNb2O6 diffused into the lattice of Bi 0.5Na0.5TiO3 to form a solid solution with perovskite-type structure. A diffuse character was proved by the linear fitting of the modified Curie-Weiss law. The temperature dependence of dielectric constant at different frequencies revealed that the solid solution exhibited relaxor characteristics different from classic relaxor ferroelectrics. The samples with x = 0002 and 0006 exhibited obvious relaxor characteristics near the low temperature dielectric abnormal peak, Tf, and the samples with x = 0.010 and 0.014 exhibited obvious relaxor characteristics between room temperature and Tf. The mechanism of relaxor behaviour was also discussed according to the macro-domain to micro-domain transition theory. © Indian Academy of Sciences.