Study of low temperature-dependent structural, dielectric, and ferroelectric properties of BaxSr(1−x)TiO3 (x = 0.5, 0.6, 0.7) ceramics

Abstract

Dielectric studies of sintered pellets of barium strontium titanate, BaxSr(1−x)TiO3 (BST) with different compositions (x = 0.5, 0.6, 0.7) were carried out as a function of temperature in the range 35–297 K. The phase transformation temperature of cubic (paraelectric), tetragonal (ferroelectric), rhombohedral (ferroelectric), and orthorhombic (ferroelectric) phases of the BST ceramics with different strontium contents has been determined. The dielectric properties of the BaxSr(1−x)TiO3 pellets have revealed that Curie temperature decreased on replacing Ba by Sr. The Curie temperatures of Ba0.5Sr0.5TiO3, Ba0.6Sr0.4TiO3, and Ba0.7Sr0.3TiO3 were found to be 245 K, 260 K, and 285 K, respectively. Further, cubic, tetragonal, orthorhombic, and rhombohedral phases were observed for the BST pellets with x = 0.5, 0.6, 0.7 in the low temperature range of 35–297 K. The dielectric studies revealed higher dielectric constant and low dielectric loss for Ba0.6Sr0.4TiO3 sample than that of other compositions of the BST. Polarization–electric field (P–E) hysteresis loop measurements for Ba0.6Sr0.4TiO3 ceramic pellet was carried out with different applied electric fields in the range 1.39 to 4.86 kV/cm and in the temperature range of 108–323 K to study the variation in remanent polarization (Pr), saturated polarization (Ps), and coercive field (Ec). The saturated polarization and remanent polarization were found to increase steadily up to the temperature of 165 K and to decrease drastically at about 323 K as a consequence of ferroelectric to paraelectric transition.