Effect of Different Sintering Processing on the Microstructure of K0.5Na0.5NbO3 Ceramics

Lead-free K0.5Na0.5NbO3(KNN) piezoelectric ceramics were prepared by conventional solid-state reaction technique and sintered through conventional and hot-pressing sintering process respectively.The effects of sintering method and annealing temperature on the microstructure,morphology and density of KNN ceramics were investigated.The crystallographic structure of KNN ceramic was investigated by X-ray diffraction(XRD) and the fractured microstructures of sintered ceramics were characterized by scanning electronic microscope(SEM).The results show that all specimens exhibit pure perovskite structures.However,compared with the sample prepared with conventional sintering,higher relative density(greater than 98%),smaller grain size(0.6 μm) and lower tanδ(≤2.8%,1 kHz) are obtained in the KNN ceramics sintered through hot-pressure sintering process,meantime various particle sizes and densities of KNN ceramics can be obtained by selecting suitable annealing temperature.