Structure and dielectric behavior of nano-structure ferroelectric BaxSr1−xTiO3 prepared by sol–gel method

Nano-crystalline Ba1−xSr(x = 0.1 and 0.5)TiO3, (B10ST and B50ST) powders have been prepared by sol–gel method, using barium acetate (Ba(Ac)2), titanium butoxide (Ti(C4H9O)4), and strontium bromide as precursors. The prepared samples in the form of powder were found to be amorphous, which crystallized to the tetragonal phase after sintering at heat treatment temperature 750 °C in air for 1 h. For the Ba(1−x)S0.1TiO3 powder, which have a crystallite size equal about 33 nm, all major peaks corresponding to perovskite BST phase appeared with (1 1 0) as principle peak. X-ray diffraction (XRD) data were confirmed by transmission electron microscope (TEM). The dielectric measurements were carried out in the frequency range 42 Hz to 1 MHz, at temperature range between 25 °C and 250 °C. The Curie temperature was detected at 125 °C for BT, while it is detected at 110 °C and 75 °C for B10ST and B50ST, respectively. The obtained results showed abrupt decrease in the dielectric permittivity at temperatures above 125 °C and 75 °C, for pure BaTiO3 and Ba0.5Sr0.5TiO3, respectively, leading to phase transition.