Modulating Mn self-reduction and multimodal luminescence in CaSb2O6 through La3+ doping for quadruple-mode dynamic anti-counterfeiting and optical temperature sensing applications†

Luminescent materials play a key role in the field of optical anti-counterfeiting. However, the development of multimode, multi-color dynamic phosphors, making optical anti-counterfeiting more advanced and practical, remains a great challenge. Herein, multimode luminescence (PL, PersL, TL, PSL, and PSPL), dynamic multi-color emission phosphors based on a single CaSb₂O₆ (CSO) host doped with manganese ions were developed and studied in detail for the first time. The partial self-reduction of Mn in the CSO crystal was observed. The self-reduction behavior of Mn could be effectively suppressed by co-doping with La³⁺ ions through unequal substitution of the Ca²⁺ ions. Furthermore, it was found that the multimode and dynamic luminescence properties of the CSO:Mn phosphors could be further modulated by adjusting the La³⁺ doping concentration, which could be used as a new type of anti-counterfeiting materials. Here, a novel four-mode multicolor and dynamic anti-counterfeiting “rose bouquet” pattern was designed, where a portable UV lamp only having two emitting wavelengths (254 and 365 nm) was required to achieve a full anti-counterfeiting effect. This design is low-cost, easy to realize and advanced in terms of functionality, which has great potential for practical applications in the field of optical anti-counterfeiting. In addition, its temperature sensor application based on the different thermal-quenching characteristics of Mn²⁺ and Mn⁴⁺ was also evaluated.