Reversible white-brown photochromism in a self-activated long-persistent phosphor Mg_2SnO_4

Abstract

Recently, considerable attention has been paid to photochromic (PC) materials owing to its great potential application in various fields, such as rewritable copy papers, erasable optical memory media, smartwindows, sensors, photoswitches and so on. Up until now, most of PC materials come from organics. However, we report that a self-activated LAG phosphor possesses PC property based on non-doped Mg2SnO4 synthesized via a traditional solid-state reaction method. The photoluminescence and long afterglow (LAG) properties were investigated. Interestingly, the white surface color can be colored into brown by ultraviolet-light (UV) irradiation. After visible light irradiation or heat-treatment, the colored Mg2SnO4 can be bleached into white again. The reversible white-brown PC properties of Mg2SnO4 were characterized by diffuse reflectance spectra. Based on the observed phenomena and the obtained experimental results, a tentative model was constructed to illustrate the LAG and PC mechanism.