Reversible up-conversion emission and photo-switching properties in Er doped (K,Na)NbO3 ferroelectrics

The (1-x) K0.5Na0.5NbO3-xNa0.5Er0.5TiO3 [(1-x)KNN-xNET] ceramics were fabricated by the traditional solid state reaction method. The effects of the NET content on their phase structure, microstructure, photochromism and photo-switching properties were systematically studied. The samples show bright green emission (530 nm, 551 nm) and red emission (660 nm) under 980 nm stimulation at room temperature. Upon visible light irradiation (407 nm), these samples change their color from the initial pale yellow to dark grey. And, luminescence emission intensity can be easily modulated by adjusting the degree of color change. In particular, the color and up-conversion emission can return its initial state by 230 °C thermal stimulation, showing excellent reversibility. These results make it potential applications in many fields such as luminescence switching and optical storage materials as a kind of multifunctional material.