Preparation, Microstructure, and Dielectric and Ferroelectric Properties of Modified (1 – x)(K0.5Na0.5)NbO3⋅xLiNbO3 Ceramics

Single-phase (1 – x)(K0.5Na0.5)NbO3⋅xLiNbO3 (KNN–LN) perovskite-structure ceramic materials with x = 0–0.10 modified with CuO and KCl additions have been prepared by solid-state synthesis, and their phase composition, structure, microstructure, and dielectric and ferroelectric properties have been studied. Increasing the percentage of lithium niobate has been shown to increase their Curie temperature and lower the temperature of their polymorphic phase transition, which is accompanied by a decrease in perovskite cell parameters, in accord with the ionic radii of the A-site cations. The x = 0.2 material has been found to have an increased room-temperature dielectric permittivity, which correlates with the observed increase in spontaneous polarization, as evidenced by laser radiation second harmonic generation intensity measurements.