Enhanced dielectric and ferroelectric behavior in 0.94BNT-0.06BCTS lead free piezoelectric ceramics synthesized by the solid state combustion technique

Abstract

ABSTRACTIn this study, the effects of calcination temperature (600–900°C for 2 h) and sintering temperature (1100–1200°C for 2 h) on phase formation, microstructure and electrical properties of new 0.94(Bi0.5Na0.5TiO3)-0.06(Ba0.945Ca0.055)(Ti0.91Sn0.09)O3 (0.94BNT-0.06BCTS) lead-free piezoelectric ceramics were investigated. These ceramics were fabricated by the solid state combustion technique using glycine as fuel. It was found that single perovskite phase of 0.94BNT-0.06BCTS powders is obtained by the sample calcined at 650°C for 2 h. The microstructure of the 0.94BNT-0.06BCTS powders showed an almost-circle shape and the average particle size increased from 218 to 298 nm when the calcination temperature was increased from 600 to 900°C. The XRD pattern of all ceramics presented a single perovskite structure with the co-existence of the rhombohedral and tetragonal phase. The average grain size increased with increasing sintering temperature. The density, dielectric constant (at Tr and Tm) and piezoelectric constant (d33) increased when sintering temperature was increased up to 1150°C and then, reduced in values, respectively. At a sintering temperature of 1150°C, 0.94BNT-0.06BCTS ceramic exhibited the highest density (5.95 g.cm−3), the highest dielectric constant at Tm (ϵmax = 6210), the strongest ferroelectric properties (Pr = 43.4 μC/cm2 and Ec 37.68 kV/cm) and the highest d33 value (189 pC/N). The large ferroelctricity in 0.94BNT-0.06BCTS ceramic make them good candidates for lead-free practical applications as a ferroelectric capacitor.