Effect of MnO₂ Modification on Structure and Dielectric Properties of K0.5Na0.5NbO₃ Ceramics

Abstract

This study investigates the effect of manganese dioxide (MnO₂) doping on the structural and dielectric properties of potassium sodium niobate (K₀.₅Na₀.₅NbO₃, KNN) ceramics. KNN ceramics with varying MnO₂ concentrations were synthesized via the solid-state reaction method, and their dielectric properties were comprehensively characterized. The results indicate that all MnO₂-doped KNN ceramic samples exhibit a typical tetragonal perovskite structure. An appropriate amount of MnO₂ doping significantly enhances the dielectric properties of KNN ceramics. However, excessive doping leads to performance degradation, although the properties remain superior to those of pure KNN ceramics. Under optimal MnO₂ doping conditions, the dielectric constant gradually increases, indicating enhanced polarization intensity and dielectric performance. Furthermore, MnO₂ doping reduces the dielectric loss of KNN ceramics. At low frequencies, the dielectric constant of all KNN ceramic samples increases with temperature due to structural changes induced by doping; however, beyond a specific temperature threshold, the dielectric constant begins to decline. This finding is crucial for electronic devices operating within particular temperature ranges.