Lead-free relaxor ferroelectric ceramics with high optical transparency and energy storage ability

Abstract

We prepared highly transparent relaxor ferroelectric ceramics based on (K_0.5Na_0.5)NbO₃ using a pressure-less solid-state sintering method without using hot isostatic pressing and spark plasma sintering. A high energy storage density of 2.48 J cm⁻³ and high transparency in the visible region (ca. 60% at 0.7 μm) were achieved for the 0.8(K_0.5Na_0.5)NbO₃–0.2Sr(Sc_0.5Nb_0.5)O₃ ceramics with submicron-sized grains (about 0.5 μm). The energy storage density of 2.48 J cm⁻³ exceeded all previous reports for lead-free bulk ceramics. These results demonstrate that the 0.8(K_0.5Na_0.5)NbO₃–0.2Sr(Sc_0.5Nb_0.5)O₃ ceramics are promising lead-free transparent dielectric materials for use in transparent electronic devices. This study not only opens up a new avenue for the design of lead-free transparent ferroelectric ceramics with a high energy storage density, but also expands the applications of (K_0.5Na_0.5)NbO₃-based ceramics into new areas beyond piezoelectric applications.