Investigation of dielectric transitions and impedance behavior in solid solutions of (1-x) K₀.₄₁Na₀.₅₉Nb₀.₉₅₉Sb₀.₀₄₁O₃-x(Bi₀.₅K₀.₅TiO₃), synthesized by solid state reaction method

In this study, we present the results of structural, impedance, modulus and conductivity analysis of (1-x) K_0.41Na_0.59Nb_0.959Sb_0.041O₃-x(Bi_0.5K_0.5TiO₃) (x = 0.01, 0.03, 0.05 and 0.07) (KNNS-BKT) polycrystalline ceramics prepared by the conventional solid-state reaction technique. The X-ray diffraction pattern (XRD) for all synthesized polycrystalline samples confirmed the formation of a pure perovskite phase. KNNS-BKT ceramics exhibit an orthogonal-tetragonal phase boundary at room temperature for composition x = 0.01 and 0.03. In the KNNS system, BKT induces a diffuse transition, but no significant shift in T_o−t and Tt-c with frequency is observed. A slight variation in lattice parameters was observed at different concentration of x in KNN-BKT ceramics. The average crystalline size and lattice strain of KNNS-BKT ceramics were evaluated by using the Williamson-Hall plot to study the composition dependence. The dielectric constant (ε) increased with higher concentration. All samples exhibited a NTCR semiconducting nature.