NaYTi₂O₆: Pr³⁺ phosphors enabling dual-mode optical thermometry and persistent luminescence for anti-counterfeiting

Developing multifunctional phosphors suitable for both anti-counterfeiting and optical thermometry applications remains challenge. Herein, a series of NaYTi₂O₆: Pr³⁺ phosphors were synthesized, and their luminescence properties, temperature sensitivity and potential applications were systematically investigated. Under ultraviolet excitation, the phosphors exhibited prominent red emission at 614 nm (¹D₂ → ³H₄) along with weaker emissions centered at 690 nm (³P₀ → ³F₃). Notably, red persistent luminescence (PersL) can also be observed from the NaYTi₂O₆: Pr³⁺ phosphor. Based on thermoluminescence analysis, a feasible persistent afterglow mechanism of the phosphors was presented and discussed. Furthermore, luminescent patterns are fabricated by utilizing these phosphors as inks for anti-counterfeiting applications. In addition, the thermometric mode based on the normalized integrated intensity over 580-650 nm delivers a maximum relative sensitivity (S_r) of 2.77%K^-1. Further FIR thermometry constructed from the Pr^{3+ 1}D₂ → ³H₄ and ³P₀ → ³F₃ transitions achieves a higher maximum S_r of 4.02%K^-1. These results indicate that NaYTi₂O₆: Pr³⁺ phosphor with persistent luminescence has potential applications in anti-counterfeiting and optical thermometry.