Investigation of the structural, optical and dielectric properties of La-doped BaTi0.97Y0.03O3 ceramic

A series of Lanthanum (La)-doped BaTi0.97Y0.03O3 ceramics were successfully prepared using the sol gel process and their structural, microstructural, optical and dielectric properties investigated. The X-ray diffraction (XRD) patterns of all the as-prepared samples showed a tetragonal phase without the presence of any secondary phase which was also confirmed by Rietveld refinement. Raman spectroscopy analysis revealed the appearance of the A1g mode, which can be considered as the signature of the co-doping with La at the Ba-sites and Y at the Ti-sites in the BaTiO3 matrix. Scanning electron microscopy (SEM) analysis revealed a decrease in grain size with the incorporation of La into the BaTi0.97Y0.03O3 matrix. Ultraviolet–Visible (UV–Vis) spectroscopy results showed that La did not significantly influence the band gap energy of the BaTi0.97Y0.03O3 matrix and therefore it preserved its insulating character in contrast to other dopants (Iron, Samarium) as reported in the literature. Dielectric measurements showed that doping with La lowered both the temperature value of the maximum of the permittivity (Tm = 44 °C for x = 5% at 10 kHz) and of the dielectric losses (tan δ