Grain size engineered K 0.5 Na 0.5 NbO 3 ceramic with enhanced piezoelectric properties by introducing Zn additive

Developing lead-free piezoelectric materials is crucial for replacing lead-contained materials in electronics. In this study, we address the challenges of low breakdown strength and poor sinterability in (K, Na)NbO 3 (KNN) ceramics by introducing Zn as a sintering aid. The effects of Zn concentration on the structure, breakdown strength, dielectric, and piezoelectric properties of KNN ceramics have been investigated. The Zn-modified KNN ceramics exhibited a dense microstructure with reduced grain size and high breakdown strength. Remarkably, the grain size engineered KNN- x Zn ( x = 0.02) ceramic demonstrated a significantly enhanced d 33 value of 97 pC/N, which was 47% higher than that of the pure KNN ceramic. Simulation results revealed that the accumulation and discharge of electric charges on the surface of undissolved ZnO, due to its high electrical conductivity, led to a degradation in the piezoelectric property. These findings provide insights into the design of lead-free piezoceramics and offer a feasible approach for developing novel KNN-based materials for electromechanical transduction applications.