MnO2-modified 0.98(K0.5Na0.5)NbO3–0.02LaFeO3 ceramics with low dielectric loss for high temperature ceramics capacitors applications

The MnO2-doped 0.98(K0.5Na0.5)NbO3–0.02LaFeO3 [0.98KNN–0.02LF-x] lead-free ceramics were prepared by the conventional solid-state sintering method. The effects of MnO2 doping on the phase structure, microstructure, and electrical properties of the ceramics were investigated. The results reveal that MnO2 is an excellent sintering aid for the 0.98KNN–0.02LF-x ceramics to improve the densification and decrease the sintering temperature. Additionally, the MnO2 doping significantly increases the dielectric permittivity and decreases the dielectric loss of the 0.98KNN–0.02LF ceramics. The 0.98KNN–0.02LF-1.5 mol% ceramics show excellent high temperature dielectric properties: the dielectric permittivity εr is approximately 2000 and dielectric loss tgδ is smaller than 3% at a broad temperature range from 100 to 400 °C.