Novel orange-emitting Ba₂LaNbO₆:Eu³⁺ nanophosphors for NUV-based WLEDs and photocatalytic water purification

Energy conservation and environmental safety are the key requirements in the modern world. We report novel orange-emitting double perovskite Ba₂LaNbO₆:Eu³⁺ (BLN:Eu³⁺) nanophosphor fabricated using a citrate sol-gel method for use in general illumination and photocatalysis. After annealing at 800 ℃ the particles exhibited a nanorod-like morphology with monoclinic structure. The photoluminescence emission spectra exhibited an intense ⁵D₀→⁷F₁ transition at 594 nm and a moderate ⁵D₀→⁷F₂ transition at 615 nm, demonstrating that the Eu³⁺ ions occupied the La³⁺ sites with inversion symmetry. The optimal concentration of Eu³⁺ ions was found to be about 5 mol% for the BLN host lattice. Energy transfer from the NbO₆ ^7- octahedrons to the Eu³⁺ ions was clearly witnessed when the BLN:Eu³⁺ nanophosphors were excited with both the characteristic excitation bands of Eu³⁺ (⁷F₀→⁵L₆) and NbO₆ ^7- octahedrons at 392 and 380 nm, respectively. The thermal quenching temperature of 5 mol% Eu³⁺ ions doped BLN nanophosphors was found to be 183 ℃ indicating that these nanophosphors are very stable at high temperatures. In addition, the dye removal efficiency of the proposed BLN nanophosphors was verified using Rhodamine B (RhB) dye as a model pollutant under UV irradiation. Compared to a commercial nano-ZnO catalyst, our synthesized BLN nanophosphors showed superior RhB de-colorization efficiency. Therefore, the proposed BLN:Eu³⁺ nanophosphors are promising multifunctional materials for photocatalysis and general lighting applications.