Influence of BaTiO3 on synthesis and structure of lead-free ceramics based on KNN

In the present work lead-free compositions with a stoichiometric formula (1-x)(K_0.5Na_0.5)Nb_1-ySb_yO₃-xBaTiO₃ (x=0.01, 0.02, 0.04; y=0.04, 0.07) were produced by solid state sintering method. Manganese oxide MnO₂ was used as a dopant in order to lower the sintering temperatures. The influence of BaTiO₃ on the microstructure, density, mechanical and electrical properties of Sb-substituted KNN ceramics was investigated. X-ray diffraction analysis revieled pure perovskite structure. Microstructural investigation of the ceramics samples showed homogeneous structure with a slightly rounded cubical grain shape. Phase transition temperature T_c is shifted to lower temperatures in comparison to Sb-substituted KNN ceramics. Phase transition peak at T_c becomes broader indicating the diffuse phase transition.