Potassium sodium niobate-based transparent ceramics with high piezoelectricity and enhanced energy storage density

Lead-free potassium sodium niobate (KNN)-based transparent ceramics are highly desirable owing to their excellent piezoelectricity, and recoverable energy storage density (W_rec) especially for optoelectronic devices. However, it is challenging to achieve all parameters such as efficient light transmittance and excellent piezoelectricity or energy storage performance in a single device. Herein, we report a facile fabrication of transparent ceramic composed of (1 – x)[(Na_0.57K_0.43)_0.94Li_0.06][(Nb_0.94Sb_0.06)_0.95Ta_0.05]O₃-xCaZrO₃ (x = 0, 0.01, 0.03, 0.05, 0.07, 0.09 and 0.10) ((1 – x)KNLNST-xCZ) via conventional solid-state reaction method. It has been found that ceramics can retain good light transmission and maintain their piezoelectric properties by adjusting the phase structure and refining the grains to a certain extent. In particular, KNLNST-based transparent ceramic with 0.07CZ modifications demonstrates a high transmittance (T = 73.5% at 1800 nm) and exceptional piezoelectric constants (d₃₃ = 130 pC/N), which is more efficient than reported KNN-based transparent ceramics. More importantly, a significant improvement in grain size refinement is also achieved through the integration of CZ into KNLNST, which allow us to increase the breakdown strength of the ceramics while improving their light transmittance, which result in a high density of energy storage. The highly efficient energy storage performance (W_rec = 4.88 J/cm³) and the higher transparency (T = 75% at 1800 nm) at 0.91KNLNST-0.09CZ ceramic. We believe that this work will provide useful strategies for the development of KNN-based functional ceramics.