Excitation‐dependent afterglow evolution based on constructing dual crystal field glass ceramics

Abstract Distinctive luminescent properties and excellent stability of long persistent luminescent (LPL) glass‐ceramic hold promise for anti‐counterfeiting and encryption applications. However, rational synthesis and a deep understanding of the precipitation of dual‐phase microcrystals in glass substrate to improve the encryption level remain challenging. Here, we carefully designed the components based on the phase diagram and combined them with the glass‐forming region. By utilizing the different crystallization behaviors of SrAl 2 O 4 and CaAl 2 O 4 in the glass matrix to realize dual crystals coexistence in a borate glass matrix, which provides different crystal field environments for Eu 2+ luminescence, thus obtaining excitation‐dependent tunable LPL characteristics in a single sample. Mechanism studies unveiled that this excitation‐dependent behavior arises from the differential capture of charge carriers by defect oxygen vacancies in the sample when charged with different laser sources, providing a channel for multimode anti‐counterfeiting encryption. This strategy of constructing a double crystal field in a glass matrix overcomes the stringent requirements of a single heat treatment method for the crystallization temperature of biphasic crystals, which could become a stable and promising advanced anti‐counterfeiting encryption material and provide new insights into the multi‐band luminescence regulation of rare earth ions.