The Defect Regulation Engineering Based on Alkaline Metal for Enhancing the Long Persistent Luminescence and Thermal Stability

Abstract Despite remarkable progress in the development of efficient and tunable long persistent luminescence (LPL) materials, current systems still face limitations in effectively controlling their thermal stability. This fundamental constraint presents a major scientific challenge in realizing simultaneous tuning of both LPL properties and thermal stability within a single material system. Therefore, an alkaline metal is proposed for defect regulation engineering to modulate luminescence performance, thermal stability, and LPL duration time. Li + co‐doping acts as a flux agent and charge compensator, optimizing the lattice parameters and enhancing the Tb 3+ luminescence intensity by more than threefold in CaGa 4 O 7 :Tb 3+ . Crucially, the number of defects significantly increased by ≈10.4‐fold without introducing new defect type, leading to a more than fourfold improvement in LPL duration time. Most notably, the anti‐thermal quenching performance is dramatically enhanced, the luminescence intensity of Tb 3+ reaches 432.6% and 125% of its initial value at 443 and 563 K, demonstrating excellent stability and reversibility. Due to the combination of the inherent blue‐white emission quenching of CaGa 4 O 7 and the compensation effect of defects on Tb 3+ luminescence, a dynamic luminescence color shift from blue–green to green is observed. Therefore, this work unveils the potential for more sophisticated anti‐counterfeiting applications and reversible high‐temperature indicators.