Deep Trap Quaternary Complex Spinel for Temperature‐Gated Decryption: Inducing High Storage Capacity by Cation Intermediate Occupancy

Abstract Deep trap persistent luminescence materials with high storage capacity are highly demanded for efficient long‐term information encryption and cyclic imaging. The total storage capacity is determined by the trap depth distribution. Apart from deliberate impurity‐induced traps and the manipulation of intrinsic lattice defects by synthesis conditions, the generation of defects is also closely related to the site coordination geometry of the host. A series of quaternary complex spinel materials Zn a Ga 1.99a Mg 2 SnO 4+4a : a0.01Cr 3+ (ZGMSO) are designed by combining spinel ZnGa 2 O 4 and inverse spinel Mg 2 SnO 4 through the strategy of cation intermediate occupancy. Density functional theory (DFT) calculations reveal that the introduction of Mg 2+ and Sn 4+ promotes antisite defects and O vacancies (V O ). Temperature‐dependent excitation thermoluminescence (TL) experimental results show that a larger trap capacity is generated for a representative sample ZGMSO3. TL fading experiments show that ZGMSO3 has increased density of deep trap with a depth ranging from 0.9 to 1.3 eV. The application of optical information storage can be achieved via ZGMSO3 due to deep traps, even it is experienced an extreme thermal cleaning of 150 °C. Furthermore, ZGMSO3 demonstrates temperature‐gated information encryption and decryption, and the proposed temperature‐gated decryption mechanism offers a novel approach for information security and anti‐counterfeiting applications.