Effect of KNN doping on the dielectric properties of BaTiO 3 lead-free ceramics

In this study, the phase structure, microstructure, and dielectric properties of BT-xKNN ceramic prepared by traditional solid-phase method were studied. The diffraction peaks of KNN-doped BaTiO 3 ceramics shifted to high angles. Excessive KNN doping inhibited BaTiO 3 grain growth. KNN doping improved the dielectric constant of BaTiO 3 ceramics. When the amount of KNN doped was 0.5 wt%, the dielectric constant can reach 19,359.4. When KNN was doped at 1wt%, the dielectric peak was broadened and the dielectric temperature stability was good. However, the incorporation of KNN increased the dielectric loss of BaTiO 3 ceramics, which may be caused by the increase in conduction loss caused by Nb 5+ . Moreover, the incorporation of KNN did not increase the Curie temperature of BaTiO 3 ceramics, but decreased it, which may be related to the decomposition of KNN during high-temperature sintering.