Long-lasting time-dependent tunable afterglow in Zn2SiO4:Mn2+ glass ceramics for dynamic anti-counterfeiting

Abstract

Dynamic time-dependent afterglow materials have shown good application potential in the field of anti-counterfeiting. However, their short decay time (<10 s) causes poor concealment and limits their application expansion. In this work, multiple afterglow emission centers with different decay rates have been produced in stable zinc silicate glass ceramics by phase transformation through a heat-treatment method, causing an effective long-lasting (>600 s) time-dependent afterglow that is tunable from orange/yellow to red. Mechanism analysis suggested that this is related to the varied substitution tendency of alkali metal ions into different phases (α,β-Zn₂SiO₄), leading to different depths of oxygen vacancies, which are favorable for room-temperature afterglow. Finally, we propose a novel anti-counterfeiting encryption strategy that can return different information by changing the observation frequency.