Achieving Multicolor Anti‐Counterfeiting via Simultaneous X‐Ray and UV/Blue Excitation in Ca₂YMgScSi₃O₁₂: Mn²⁺

Abstract Optical materials have attracted much attention in anti‐counterfeiting applications due to their visualization and multi‐emission modes. However, the unit occupancy predestines the material to only monochromatic emission, inhibiting the application of optical materials in advanced information encryption. Here, a green to yellow to deep‐red phosphor is reported in a Mn²⁺‐activated garnet compound Ca₂YMgScSi₃O₁₂: Mn²⁺ (CYMSS: Mn²⁺), originating from the abundant lattice sites occupying within the crystal structure by Mn²⁺ ions. Three different photoluminescence (PL) emission bands peaked at 517, 576, and 720 nm from ⁴T₁ (G) → ⁶A₁ (S) are observed, which are attributed to the substitution of [Sc/MgO₆] octahedron and [Ca/YO₈] dodecahedron sites by Mn²⁺ ions, respectively. Hence, tunable emissions from green to deep‐red are realized in single Mn²⁺ doping by switching the excitation source of ultraviolet (UV)/blue and X‐ray, which can be further regulated by varying the Mn²⁺ concentration. Multi‐position occupying, color‐tunable light‐emitting materials offer the possibility of more advanced optical information encryption.