Thermally-stable Sm3+-activated Ba6La2Ga4O15 red phosphor for multifunctional applications: Optical thermometry, WLEDs and latent fingerprint visualization

Existing phosphor materials can hardly meet the demands of multi-scenario applications. The importance of developing novel Sm 3+ doped phosphors with both excellent thermal stability and multifunctional properties is thus emphasised. This paper presents a systematic study of the multifunctional red phosphor Ba 6 La 2 Ga 4 O 15 :Sm 3+ . Under 406 nm excitation, the material exhibits a characteristic red-light emission of 601 nm. Thermal stability tests showed that its luminescence intensity at 423 K maintained 81.84 % of room temperature. The thermometry performance based on the FIR method showed a maximum relative sensitivity of 1.89 %/K and an absolute sensitivity of 0.63 %/K in the range of 298 – 473 K. Application studies show that the encapsulated WLED device has a color temperature of 4878 K and a color rendering index of 91.4, making it suitable for high-rendering white light illumination; In addition, the phosphor enables high-contrast imaging of fingerprint features at levels 1 – 3, which significantly improves latent fingerprint recognition rates. In conclusion, BLGO:Sm 3+ phosphors have shown significant application value in the fields of non-contact optical temperature measurement, high-quality solid-state lighting and fingerprint monitoring.