The dielectric and ferroelectric properties of (Ba0.5Sr0.5)TiO3-doped (Bi0.5Na0.5)TiO3 lead-free ceramics

Abstract

This work prepares (Ba0.5Sr0.5)TiO3 (BST)-doped (Bi1/2Na1/2)TiO3 (NBT) lead free ceramics through conventional solid reaction method and analyzes the doping effect of BST on phases, microstructure, dielectric and ferroelectric properties. The phase and structure of the NBT-BST ceramics were investigated through X-ray diffractometer (XRD) and Raman. The XRD results showed that BST has diffused into the NBT lattices to form a stable solid solution; while, Raman spectrum showed the bands at low frequency are different with that of pure NBT and divided into two ranges around 247 cm-1 and 303 cm-1. Relative dense and homogeneous ceramic microstructures could be achieved, with the observation of a slight decrease in average grain size with the increase of BST doping content. The dielectric and ferroelectric properties were also investigated. The dielectric constant increases gradually with increasing the temperature to Tm, and then decrease. The temperature dependence property showed diffused phase transition near Tm. The polarization-electric field (P-E) hysteresis loops of BST-doped NBT ceramics showed typical ferroelectric or relaxor nature. Both the Ec and Pr increased first, then decreased with respect to the increase of the BST content.