Enhanced optical and energy storage properties of K0.5Na0.5NbO3 lead-free ceramics by doping Bi(Sr0.5Zr0.5)O3

Abstract

Transparent relaxation ferroelectric ceramics with excellent transmittance and energy storage density are indispensable for efficient multifunctional coupling. These ceramics have found extensive applications in transparent energy storage electronics, advanced pulsed power capacitors, and optoelectronic multifunctional devices. In this study, we employed a combination of strategies to enhance the optical and electrical properties of ceramics. Specifically, the breakdown field strength of potassium sodium niobate (KNN) was increased by introducing Bi(Sr0.5Zr0.5)O3 (BSZ), which reduced the ceramic grain size. The incorporation of polar nano-micro-regions led to stronger local polarity fluctuations on the nanoscale, effectively minimizing the residual polarization. Furthermore, the forbidden bandwidth of the system was widened to mitigate photoelectron optical energy loss during transition.The newly developed ceramic, (1-x) KNN-xBSZ, exhibited remarkable performance characteristics, including an energy storage density of 4.13 J/cm3, a recoverable energy storage density of 2.95 J/cm3 at a low electric field of 245 kV/cm, and an energy storage efficiency of 84 %. Additionally, at 700 nm, the 0.875KNN-0.125BSZ sample displayed a transmittance of 52 %. Notably, this ceramic demonstrated high power density (PD = 36.76 MW/cm3) and rapid charge/discharge rates (t0.9 = 0.94 μs). Moreover, it exhibited excellent temperature and frequency stability, making it a dependable option for optoelectronic devices utilizing transparent relaxation ferroelectric ceramics.