Preparation and characterization of sodium potassium niobate lead-free ceramics and middle frequency resonator

K4CuNb8O23 (KCN) modified (Na0.5K0.5)NbO3 lead free piezoelectric ceramics were synthesized by using oxide powder method. The crystalline structure was characterized by X-ray diffraction (XRD) and with combination of electronic scan microscopy (SEM). Dielectric constant dependence of temperature at different frequency and piezo-, ferroelectric properties were also investigated. It was found that the enhanced piezoelectric properties were obtained when of KCN was added into NKN. The maximum mechanical quality factor Qm and planar electromechanical coupling coefficient kp reach up to 1550 and 40%, respectively. Middle frequency resonators (455kHz), which are largely used in TV, VCD, controller, etc., based on NKN-based ceramics were designed and produced. Results show this kind of lead free middle frequency resonators have great promising in substituting of lead-based frequency devices.