High performance lead-free Na0.5K0.5NbO3 piezoelectric ceramics obtained via oscillatory hot-pressing

Abstract

Lead-free Na0.5K0.5NbO3 (KNN) piezoelectric ceramics is regarded as a potential candidate for PZT material, while high performance is difficult to be obtained due to its poor sinterability and non-stoichiometric component. In this work, oscillatory pressure-assisted hot pressing (OPAHP) is utilized to fabricate KNN ceramics with high density. The KNN ceramics sintered at 860 °C exhibits superior performance with piezoelectric parameter (d33) of 142 pC/N, electromechanical coupling factors (kp) of 0.41, and relative permittivity (εT33/ε0) of 472–620. Additionally, hardness and flexural strength are measured as 3.55 GPa and 99.13 MPa, respectively. This work indicates that OPAHP technique is effective for fabricating KNN piezoelectric ceramics with high performance.