Ceramics-Silikáty 58 (1) 28-32 (2014)

EFFECT OF B-SITE SUBSTITUTIONS OF Nb ON MICROSTRUCTURE, PHASE TRANSITION TEMPERATURES AND ELECTRICAL PROPERTIES OF (Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃ CERAMICS

Niobium (Nb) substituted bismuth sodium barium titanate (BNBT) samples with general formula (Bi_0.5Na_0.5)_0.94Ba_0.06 (Ti_1-5x/4Nb_x)O₃, where x = 0, 0.003, 0.012 and 0.05 were prepared by solid state reaction method. The crystal phase, microstructure, electrical properties and phase transition temperatures of these materials were investigated. Samples consisted entirely of rhombohedral structure was formed. Scanning electron micrographs (SEM) revealed enhanced microstructure uniformity and retarded grain growth with increasing niobium content. Dielectric measurement as a function of temperature at variable frequency showed that the dielectric constant gradually decreases with niobium doping. The Curie temperature, T_C, got shifted to lower temperature as the amount of dopant increases.

Keywords: (Bi_0.5Na_0.5)TiO₃, Dielectric, Ferroelectric, Sintering, Microstructure