Thermally Stable Orange-Red BaLaLiWO6:Sm3+/Sr2+ Phosphors for Potential Application in Plant Growth

Phosphor of BaLaLiWO 6 doped with lanthanide activators Sm 3+ and Sr 2+ was successfully achieved via a high-temperature solid state reaction. Powder X-ray diffraction analysis confirmed that the phosphors crystallize in a cubic crystal system with the space group F m-3m could be correlated with the structural changes after Sm-doping. Scanning electron microscopy images revealed irregular morphology, the material crystallized particles aggregated and were non-uniform with particle sizes ranging from 1 to 9 μm. Under 405 nm excitation, the phosphor exhibited four narrow emission peaks in the range of 500 − 750 nm, resulting from the 4 G 5/2 – 6 H 5/2 , 6 H 7/2, 6 H 9/2 and 6 H 11/2 transitions of Sm 3+ ions. The substitution of Sr 2+ for Ba 2+ altered the local environment of the luminescent ions, resulting in a significant increase in the emission of the Ba 0.2 Sr 0.8 La 0.92 LiWO 6 : 0.08Sm 3+ sample, with an approximately 66% enhancement. Notably, the phosphor also demonstrated outstanding thermal stability, retaining 89% of initial intensity at 425 K. When integrated with an InGaN LED chip, the electroluminescence spectrum of Ba 0.2 Sr 0.8 La 0.92 LiWO 6 : 0.08Sm 3+ closely matched the absorption spectrum of the PR pigment in plants, indicating strong potential for use in solid-state lighting applications for plant growth.