DIELECTRIC PROPERTIES OF BARIUM STRONTIUM TITANATE CERAMICS AT 20 Hz TO 1 MHz

Abstract

Perovskite-based ferroelectrics of Barium Strontium Titanate (BST; x=0.3-0.7) have been prepared using conventional solid-state method. The XRD showed that BST ceramics were perovskite structure without occurring secondary phase after sintered at 1200°C. However, sample x=0.3 was tetragonal phase while x=0.4-0.7 were cubic phase due to the ease of tetragonal-cubic phase transition as the strontium content increased. BST were frequency and temperature dependent. However, dielectric constant of Ba_0.6Sr_0.4TiO₃ decreased with increasing of measuring temperature. This was due to the occurrence of impurities which diffused the dielectric constant. Beside this, non-homogeneous distribution of Ba²⁺ and Sr²⁺ would also produce the diffused phase transition response. B_a0.5Sr_0.5TiO₃ had the highest dielectric constant.