Eu-doped K0.5Na0.5NbO3-(Ba, Sr)TiO3: A novel lead-free luminescent ferroelectric transparent ceramic with reversible photochromism

Photochromic (PC) luminescent ferroelectric materials have aroused great interest because of their potential applications in optical information memories, optical switches and bio-imaging. However, those materials are basically opaque. In this work, we prepared a PC luminescent K0.5Na0.5NbO3-based ferroelectric transparent ceramic by modifying with Eu3+, Ba2+, Ti4+ and Sr2+, which not only have good optical transmittances (similar to 60% at 900 nm), moderate ferroelectric properties and down-conversion photoluminescence (PL) properties, but also exhibit reversible PC behavior. After the illumination by xenon lamp, the colors of the ceramics change from pale green to gray, and then reversibly recover to their initial state via thermal stimulus (200 degrees C for 10 min). Interestingly, both the optical transmittances and PL intensities can be effectively tailored by controlling the PC reaction process. The results suggest that the ferroelectric transparent ceramics are promising for the modulation of photoenergy and the design of optoelectronic devices.