Effect of partial replacement of Bi on electrical properties of layer structured strontium bismuth titanate

Bismuth in SrBi4Ti4O15 is partially replaced with La3+ to synthesize SrBi(4-X) LaXTi4O15 , with x = 0.25,0.5,0.75. The samples have been prepared by sol-gel method using ethylene glycol gel and aqueous solution. This sol-gel process offers some advantages, such as homogeneity and stoichiometry control. The structural characterization of the samples is done using powder X-ray diffraction measurements. The samples are electrically characterized by using dielectric and impedance spectroscopy measurements in the frequency range of 500 Hz to 1 MHz, and temperature range from RT to 600 degrees C. These samples show strong frequency and temperature dependent dielectric relaxations. The power law dependence on a.c conductivity is evaluated. The effect of La3+ substitution on dielectric, impedance and a.c conductivity is studied. The results obtained are interpreted in terms of the pluckering and on the consequent lattice distortion that is usually present in Bismuth Layer Structured Ferroelectrics.