Effect of Sm and Na substitution on dielectric properties of SrBi4Ti4O15

Abstract

The synthesis, characterisation, density and dielectric properties of Sm and Na substituted SrBi4Ti4O15 (SBT) piezoelectric ceramics are systematically studied for possible applications at high temperatures. The existing piezoceramics have temperature limitations. Samarium (Sm) and Sodium (Na) modified Strontium bismuth titanate Sr1-x SmxNaxBi4Ti4O15 (SSNBT-Strontium Samarium Sodium Bismuth Titanate) where x = 0.1, 0.2, 0.3 ceramics are prepared by solid state double sintering method using planetary ball mill for 10 hours duration in presence of Acetone media. Single phase is formed after calcination at 800 °C for 2 hours. Pellets are made with 1 cm diameter and 1 mm thickness using uniaxial Hydraulic press at 5 tonnes/cm2 pressure. All the samples are sintered at 1160 °C for 2 hours. The entire calcination and sintering processes are done in a programmable furnace. Orthorhombic structure of compound is confirmed by XRD analysis. The lattice parameters were calculated and experimental density was found to be around 95% of theoretical density. Tolerance factor decreased with increasing concentration of Sm, Na. The plate-like structure of grains is observed using SEM images and orientation of grains is random. Dielectric properties are reported as a function of temperature at different frequencies. The Curie temperature (Tc) of SBT is enhanced by substitution of Sm and Na in place of Strontium making this material a useful piezoceramic for high temperatures applications.