Investigation of structure–property correlation on the dielectric and optical properties of lanthanum modified barium titanate ceramic

The present manuscript outlines the investigation of the structure, dielectric and optical properties of Lanthanum (La) doped BaTiO 3 (BLT) ceramic with compositions of Ba 1-x La 2x/3 TiO 3 prepared by the solid-state reaction method. The Rietveld refinement of the XRD pattern illustrates that La doping changes from tetragonal structure to cubic structure with a mixed phase in intermediate composition. The Raman spectra illustrate the existence of modes associated with tetragonal symmetry up to x = 0.05 and the disappearance of modes at 307 cm −1 confirming the cubic symmetry for higher doping concentration. The temperature variant dielectric study in the studied range reveals a two-phase transition until x = 0.05 which merges for higher concentrations. The temperature variant dielectric study expresses that the transition temperature declines whereas the dielectric constant at transition temperature increases as a function of doping content. The dielectric loss of the doped samples is found to increase until x = 0.05 and thereby decreases for higher concentration values. The temperature coefficient of the dielectric constant was calculated for all the compositions. The diffusivity was calculated using the altered Curie–Wiess law revealing that the diffusivity increases because of doping percentages. A signature of relaxor nature is obtained in the composition x = 0.1, which is confirmed by the Vogel–Fulcher (VF) fitting. The optical property of all the prepared samples has been studied using UV–Vis spectroscopy and photoluminescence.