Highly thermally stable La3SnGa5O14: Sm3+ orange-red phosphors for optical thermometers and fingerprint detection
To fulfill bifunctional applications of the optical thermometry and fingerprint detection, Sm 3+ -doped La 3 SnGa 5 O 14 phosphors were synthesized. Under 403 nm excitation, the phosphor showed strong orange-red emission with the peaks at 562, 599, 644, and 707 nm, originating from the 4 G 5/2 → 6 H n/2 (n = 5, 7, 9, and 11) transition of Sm 3+ . Interestingly, La 3 SnGa 5 O 14 : Sm 3+ had excellent thermal stability of the PL peak at 599 nm and anti-thermal quenching property of the PL peak at 562 nm. Leveraging this unique behavior, an optical thermometer based on the fluorescence intensity ratio (FIR) was designed and had a maximum relative sensitivity (S r ) of 0.2348 % K −1 at 423 K. Furthermore, the fluorescent latent fingerprints images prepared with La 3 SnGa 5 O 14 : Sm 3+ phosphor were well visualized, and the level 1–3 features could be identified under ultraviolet irradiation. These findings suggest that the La 3 SnGa 5 O 14 : Sm 3+ phosphor has potential applications in optical thermometry and fingerprint detection.
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