Effect of cerium oxide addition on optical, electrical and dielectric characteristics of (Bi0.5Na0.5)TiO3 ceramics

The composite ceramics, Bi0.5Na0.5TiO3−xCeO2 (x = 0, 0.05, 0.10, 0.15) with a general chemical composition (Bi0.5Na0.5)(Ti1−xCex)O3 were fabricated by using a solid state reaction ceramic technology. The detailed structural analysis using x-ray diffraction data exhibits the formation of composites of Bi0.5Na0.5TiO3 (BNT) and CeO2 in rhombohedral and cubic phase respectively. The Fourier transform infrared spectroscopy spectrums confirm the formation of compounds through the occurrence of characteristic peak corresponding to Ce-O, Ti-O and Bi-O bonds. With the increase in CeO2 content in the composite, the optical band gap decreases from 2.97 eV (for x = 0) to 2.45 eV for the sample (for x = 0.15). The impedance analysis confirms the contribution of grains only to the polarization and conduction processes. Two phase change corresponding to ferroelectric to antiferroelectric, and then to the paraelectric is observed at around 350 °C and 470 °C respectively. The addition of CeO2 in BNT significantly enhances the dielectric and ferroelectric properties with the decrease in loss tangent.