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

Abstract Phosphor of BaLaLiWO6 doped with lanthanide activators Sm3+ and Sr2+ 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 Fm-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 4G5/2 - 6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions of Sm3+ ions. The substitution of Sr2+ for Ba2+ altered the local environment of the luminescent ions, resulting in a significant increase in the emission of the Ba0.2Sr0.8La0.92LiWO6: 0.08Sm3+ sample, with an approximately 66% enhancement. Notably, the phosphor also demonstrated outstanding thermal stability, retaining 89% of initial intensity at 425K. When integrated with an InGaN LED chip, the electroluminescence spectrum of Ba0.2Sr0.8La0.92LiWO6: 0.08Sm3+ closely matched the absorption spectrum of the PR pigment in plants, indicating strong potential for use in solid-state lighting applications for plant growth.