Effect of La 3+ substitution on the physical properties of CaTiO 3 –0.15KNbO 3 -based lead-free ceramics

Polycrystalline samples $$ {\text{Ca}}_{0.85 - x} {\text{La}}_{x} {\text{K}}_{0.15 - x} {\text{Ti}}_{0.85} {\text{Nb}}_{0.15} {\text{O}}_{3} $$ (x = 0 and 0.05) were synthesized by the conventional solid-state reaction method. The X-ray diffraction showed that these compounds crystallized, at room temperature, in the orthorhombic structure with Pbnm space group. The scanning electron microscopy analysis showed a decrease in grain size with the La3+ substitution rate. Through the diffuse reflectance spectroscopy, we extracted the band gap energy, which decreases with the addition of La3+, which implies the improvement of the semiconductor behavior. Filament, a study on the dielectric properties, in the frequency range from 1 kHz to 1 MHz, of our samples, shows that the substitution of calcium and potassium by lanthanum in A site introduced an improvement to these properties and the appearance of a new transition.