Balancing Transparency and Ferroelectricity in K0.5Na0.5NbO3 Lead-Free Composite Ceramics

Transparent ferroelectric ceramics have garnered significant research interest in recent years owing to their unique optical transparency and electrical properties. Among them, potassium sodium niobate (KNN)-based ceramics stand out as a prominent lead-free ferroelectrics, exhibiting exceptional optoelectrical coupling performance due to their high Curie temperature, excellent ferroelectric properties, environmental friendliness, and optical transparency. In this work, an effective strategy involving multi-component doping in KNN-based materials is proposed. An energy density of 3.18 J/cm³ along with a high efficiency of 79%, and a light transmittance of 71% at 1800 nm, are achieved in K0.5Na0.5NbO3 lead-free composite ceramic, which exhibits fast discharging characteristics, with t0.9 = 1.27 μs at the current density (CD = 248.73 A/cm²) and power density (PD = 23.88 MW/cm³). The strategy provides a feasible routine for combining energy storage functionality with optical transparency, illustrating its great potential to be generally applicable in the design of lead-free composite ceramics with excellent overall performance.