Defect–Engineered Ca ₅ Ga ₆ O ₁₄ : Ti ⁴⁺ , Sm ³⁺ Multi–Stimuli–Responsive Luminescent Nanophosphor for Macro–Micro Anti–Counterfeiting and Multilevel Encoding

Abstract The escalating demand for anti–counterfeiting capabilities in the modern commodity circulation and information security sectors has promoted a growing interest in luminescent materials. However, existing anti–counterfeiting excitation modes are relatively simple, and their static optical characteristics are susceptible to spectral replication and chemical simulations. Therefore, there is an urgent need to develop novel luminescent materials with multi–stimuli–responsive properties and dynamic multi–level encryption capabilities. This study synthesizes a novel Ca ₅ Ga ₆ O ₁₄ : Ti ⁴⁺ , Sm ³⁺ luminescent nanophosphor. By collaboratively regulating the lattice distortion and trap energy levels through defect engineering, the material is endowed with tunable multi–stimuli–responsive luminescence. This material exhibits remarkable luminescence modulation under diverse excitation sources (e.g., optical, X–ray, and thermal), enabling spatiotemporal emission color tuning for advanced optical encoding and decoding. Leveraging its multimodal luminescence characteristics, a cross–scale anti–counterfeiting and encryption platform is constructed, covering macroscopic patterns, and microscopic encoding. The hidden information can only be decrypted under specific excitation conditions, greatly enhancing the complexity and security of anti–counterfeiting technologies. This study can not only advance the design of multi–stimuli–responsive luminescent materials, but also provide a viable route for applications in high–security anti–counterfeiting and information storage.