Nonstoichiometric Defect Engineering in Mn 2+ ‐Doped MgGa 2 O 4 Persistent Phosphors Toward Enhanced Luminescence and Multimodal Optical Manometry

ABSTRACT Mn 2+ ‐doped MgGa 2 O 4 persistent phosphors were synthesized through a nonstoichiometric engineering strategy to precisely regulate their luminescence properties. By introducing Mg 2+ deficiency, the luminescence intensity, thermal stability and persistent luminescence performance are simultaneously enhanced, enabling their potential application in optical anti‐counterfeiting. Furthermore, the in situ high‐pressure X‐ray diffraction measurements demonstrate the excellent structural robustness of the designed phosphors over the investigated pressure range, indicating their suitability for high‐pressure manometry. Upon compression, the resultant phosphors exhibit pronounced pressure‐induced spectral red‐shift, enabling tunable luminescence and visualized pressure sensing. Notably, compared with the stoichiometric counterpart, the Mg 2+ ‐deficient phosphors display significantly enhanced pressure responsiveness, resulting in improved optical manometric performance with higher sensitivity and an extended working pressure range. Specifically, within a broad pressure range of 0–30 GPa, the Mg 0.939 Ga 2 O 4 :Mn 2+ phosphor achieve pressure sensitivities of 5.01 and 2.29 nm GPa −1 based on the emission band centroid and full width at half maximum, respectively. Additionally, the developed phosphors exhibit good colorimetric pressure sensing capability, reaching a maximum relative sensitivity of 12.71% GPa −1 . These results demonstrate that the optical properties of the Mn 2+ ‐doped MgGa 2 O 4 phosphors can be effectively modulated through the synergistic regulation of nonstoichiometric engineering and pressure, highlighting their application potential in optical anti‐counterfeiting and multimodal manometry.