Synthesis and characterization of nanocrystalline A6Sb4ZrO18 (AÂ =Â Ca, Sr and Ba) functional ceramics

The cation deficient A6Sb4ZrO18 (A = Ca, Sr and Ba) rhombohedral perovskites are synthesized for the first time by the modified combustion method. The samples show nano size when observed through the transmission electron microscope which is in good agreement with the X-ray diffraction analysis. The tilted octahedral structure of the compounds is confirmed using vibrational spectroscopic analysis. The optical band gap of the samples is between 3.5 and 4 eV. The sintering enhances the grain growth along the c axis and hence rods like grains are observed in the scanning electron microscopic image. The impedance plots can be de-convoluted into three semicircles indicating the contribution of grain, grain boundary and electrode effects. Highest conductivity 15.14 × 10− 2 S/m is observed for Ba composition at 750 °C.