Sugato Hajra

Structural and electrical characteristics of barium modified bismuth-sodium titanate (Bi 0.49 Na 0.49 Ba 0.02 )TiO 3

The lead-free polycrystalline ceramic, barium titanate modified bismuth–sodium titanate 0.98 (Bi0.5Na0.5TiO3) + 0.02 BaTiO3 (BNT–BT-2) was synthesized by using a mixed oxide route at high temperature. The structural (crystal structure, microstructure, molecular structure), and electrical (dielectric constant and loss, impedance, conductivity) characteristics of the parent compound (Bi0.5Na0.5TiO3) have greatly been influenced by the addition of even a small amount of barium titanate in it. Preliminary structural study of BNT–BT-2 using X-ray diffraction data clearly shows the formation of a single-phase perovskite structure with the coexistence of hexagonal (major phase) and tetragonal (minor) phases. The existence of diffuse phase transtition and the relaxor behaviour in the material is confirmed by analysis of temperature-frequency dependence of dielectric parameters. The composition (0.98BNT − 0.02BT) of the material shows non-Ohmic conduction in its J–E characteristics. In this lead-free ceramic, permittivity anomalies are matched to modulus anomalies. The highlighted features are determined by structural phase transitions of the ferroelectric-like.