Synthesis and Photoluminescence Properties of Eu3+ Doped Ba3Lu4O9 Nanomaterials of High Colour Purity for LEDs Applications.

Abstract

Eu³⁺-doped Ba₃Lu₄O₉ (1-10 mol%) bright red emitters were efficiently produced through an economical solution combustion technique. Phase formation and structural analysis was executed using the obtained specific X-ray diffraction (XRD) patterns. The pure rhombohedral form of Ba₃Lu_3.8Eu_0.2O₉ sample with R3(146) space group was achieved by Rietveld refinement analysis. Field emission scanning electron microscope (FE-SEM) as well as transmission electron microscopy (TEM) provides clustered nature of particles in 60-70 nm range. The energy band-gap of host lattice (4.9 eV) and Ba₃Lu_3.8Eu_0.2O₉ composition (5.50 eV) lie within the semiconductor range enhancing the area of their application. The existence of Ba, Lu, Eu & O elements in optimum composition (5 mol%) was proved via Electron diffraction studies (EDS). Under 396 nm excitation, the dominant transition ⁵D₀ → ⁷F₂ at 621 nm is obtained which is responsible for red luminescence of Eu³⁺ ions. The Judd-Ofelt intensity parameters (Ω₂ and Ω₄) were determined based on the emission intensities corresponding to the ⁵D₀ → ⁷F₂ and ⁵D₀​ → ⁷F₄​ transitions of the europium (III) ion, respectively. Critical distance for energy transmission among nearby Eu³⁺ ions was found to be 13.71 Å. However, the colorimetric values of 5-10 mol% samples are very near to red coordinates (0.6667, 0.3333) of standard NTSC color system, and the values of CCT measured by the emission profiles fall in range of 1918 to 2942 K implying the participation of Eu³⁺ doped nanophosphor in designing warm WLEDs for indoor lighting applications.