Structure, dielectric and piezoelectric behaviors of (K,Na)NbO3 ceramics with high Q m in low-humidity by introducing SiO2 and CuO mixed oxides

Abstract

x mol% (SiO2–CuO)–K0.48Na0.52NbO3 (0.5 ≤ x ≤ 10) (SC–KNN) were prepared by the conventional solid state reaction method. The effect of SiO2–CuO mixed oxides on the crystalline structure, microstructure, dielectric and piezoelectric behaviors were studied in details. With the compositional range, all the samples were demonstrated orthorhombic symmetry according to the X-ray diffraction analysis. The mechanical quality factor (Qm) of SC–KNN ceramics was found to achieve a maximum value of 1598 when x = 5 sintered at 1110 °C in low relative humidity. Interestingly, the Qm, as well as the capacitance (Co) of KNN ceramics is sensitive to the humidity changes, which verified the stability of KNN can be affected by the humidity. The microstructure revealed that SiO2–CuO additives were effective to promote grain growth and to form a dense microstructure, which was beneficial for maintaining humidity stability.