Structural evolution and enhanced dielectric properties of CeO2 modified lead-free (Bi0.5Na0.5TiO3)-(BaTiO3) solid solutions

In this work, we investigate the structural evolution, dielectric, and conductivity properties of lead-free (0.92(Bi0.5Na0.5)TiO3-0.08BaTiO(3)) ceramic doped with CeO2 from 0.0 to 4.0 wt%. All the samples have been synthesized using a conventional solid-state reaction technique. The Rietveld refinement of X-ray diffraction data shows that all the samples exhibit dual phases of rhombohedral (R3c) and tetragonal (P4mm) crystal symmetry. It is observed from the Rietveld refinement that Ce ion diffuses into the A-site of the lattice of BNT-BT perovskite and both the phases show minimum cell volume at x = 0.03. The permittivity data confirms that the phase transition temperature does not change much but the maximum permittivity value changes with doping and the maximum dielectric constant were obtained for 3wt% doping of the CeO2 sample. The change of ac-conductivity with the temperature of the studied sample was analyzed using Arrhenius's law and Mott's variable range hopping mechanism. The fitting of the model parameters like the density of states (N(E-F)), average hopping length (R-H), and energy of hopping (W-H) were calculated for all the compositions. The activation energy associated with the samples was calculated from the Arrhenius plot, which reflects that the conduction process is different at different temperature ranges.