Effect of La3+ substitution on the physical properties of CaTiO3–0.15KNbO3-based lead-free ceramics

Abstract

Polycrystalline samples Ca 0.85−x La x K 0.15−x Ti 0.85 Nb 0.15 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 La 3+ substitution rate. Through the diffuse reflectance spectroscopy, we extracted the band gap energy, which decreases with the addition of La 3+ , 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.