Effect of Nb substitution on the structural, dielectric and modulus character of Ba0.97La0.02TiO3 ceramics

•The samples prepared using molten-salt methodof niobium.•The prepared samples crystallize in single phase, with a tetragonal structure.•As Nb-rates increases, the real and imaginary parts of the complex impedance have decreased.•The plot characterized by a single impedance semicircle.•At low frequency, followed by a linear section; was represented by the element Warburg.•The IS study revealed the presence of a semiconductor grain and an insulating grain boundary.•The conductivity decreased with the increase in the amount of niobium.