Novel potassium sodium niobate/polyimide functional composite films with high dielectric permittivity

This work reports the advanced potassium sodium niobate (K _0.5Na_0.5NbO₃, KNN)/polyimide (KNN/PI) functional hybrid films with 5 vol%, 10 vol%, 20 vol%, 30 vol%, and 40 vol% KNN loaded. The structure, morphology, and dielectric properties of hybrid films have been measured. The results show that the KNN fillers are well dispersed in the PI matrix. An internal boundary layer capacitance structure is formed in the composite films. The dielectric permittivity of the film is as high as 22 when the concentration of KNN filler reaches 40 vol% at 10² Hz, which is five times larger than that of a pure PI matrix. Meanwhile, the loss tangent is lower than 0.05. In addition, the conductivity is lower than 10^-8 (S m^-1) at 10² Hz, which indicates the excellent insulation and is important for the practical use of this kind of KNN/PI hybrid films. It is believed that the KNN/PI hybrid films could be applied in future electronic fields.