Adjustable Long-Persistent Luminescence of Zn2.1Mg0.9Ta2O8:Cr3+ Using the Multiposition Occupation and Its Application to Dynamic Anticounterfeiting

Abstract

Long-persistent luminescence (LPL) materials have been widely applied and investigated in the fields of night-safe, biofluorescent labeling and optical anticounterfeiting due to the unique properties of delayed luminescence. However, the development of a high efficiency, low cost, high precision spectral tunable deep-red LPL phosphor is still a problem to be solved. In this work, a deep-red LPL phosphor Zn_2.1Mg_0.9–xGa_xGe_xTa_2–xO₈:0.003Cr³⁺ was produced, which with four crystal structure sites can be replaced by Cr³⁺, and its luminescence properties are regulated by cation regulation engineering. The location allocation of the four luminescence centers was discussed by using TL and fluorescence attenuation curves. The introduction of [Ga³⁺–Ge⁴⁺] produces traps, resulting in LPL. With the adjustment of [Ga³⁺–Ge⁴⁺] concentration, the LPL property was increased. The brightness of the LPL has been improved, and LPL times can continue to 2 h. The mechanism of LPL and the reason for short LPL time are further analyzed by establishing the mechanism model of LPL. The application performance of phosphor can be improved by introducing [Ga³⁺–Ge⁴⁺]. A set of anticounterfeiting application models was designed based on the different decay rates of LPL. This proven ion pair substitution strategy can be used to adjust trap distribution, improve LPL performance, and develop novel phosphors with practical optical application potential.