Effect of elevated concentrations of strontium and iron on the structural and dielectric characteristics of Ba(1-x-y)Sr(x)Ti Fe(y)O3 prepared through sol-gel technique

Nano-composite Ba1-xSr(x)TiO3 (BST), where x=0.01-0.50 and doped with different concentrations of iron Ba(1-x-y)Sr(x)TiFe(y)O3 (BSTF), where x=0.01 and y=0.01-0.05 powders were prepared by sol-gel method. The effect of increasing the iron and strontium concentrations substituted in Barium strontium titanate system will be studied. The prepared samples have a tetragonal crystalline phase after sintering for 1 h at 750 degrees C in air. The structural and the morphological features of the systems have been studied using X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM). The dielectric properties of the BST and BSTF systems have been investigated as a function of temperature and frequency. The dielectric measurements are carried out in the frequency range 42 Hz-1 MHz, at a temperature ranging between 25 and 250 degrees C. The results showed a decrease in T-c temperature giving the following values 90 and 85 degrees C for B10ST and B10ST5F prepared powder samples, respectively, implying tetragonal, feroelectric phase at lower temperature into cubic, para-electric phase at temperature higher than T-c.