Optical properties and Judd-Ofelt analysis of a novel Red-Emitting monoclinic Li3Ba2Gd3(WO4)8: Eu3+phosphor

Red-emitting Li3Ba2Gd3(WO4)8: x at.% Eu3+ (0.5 <= x <= 10) phosphors were effectively produced using a conventional solid-state reaction method at high temperature in air atmosphere. The phosphors exhibited monoclinic crystalline structure with the C2/c space group and 2/m point group. The unit cell parameters determined from the Rietveld refinement for 3 at.% doped sample are a = 5.2149(4) & Aring;, b = 12.7447(1) & Aring;, c = 19.2058(3) & Aring;, alpha = gamma = 90 degrees, beta = a<^>c = 91.9315(1)degrees and Vcalc = 1275.748(2) & Aring;3. Photoluminescence spectra, lifetimes, colour coordinates and purity, and temperature-dependent emission spectra have been systematically studied. Upon excitation at 395 nm, the phosphors displayed red emission with a peak centered at 614 nm, which was associated with the 5D0 -> 7F2 electrical dipolar transition of Eu3+. At the same time, the influence of different Eu3+ ion concentration on the photoluminescence intensity is also discussed. The optimal concentration of Eu3+ ions in Li3Ba2Gd3(WO4)8 was found to be 3 at.%. The mechanism behind concentration quenching was ascribed to dipole-dipole interactions, and the critical distance for energy transfer among Eu3+ ions was determined to be 7.409 & Aring;. The Judd-Ofelt theory was utilized to assess the intensity parameters and radiative properties. The fluorescence decay times were also determined for the different concentration levels of Eu3+ cations. The chromatic coordinates of Li3Ba2Gd3(WO4)8: Eu3+ were found to be (0.653, 0.345), closely resembling the standard red light (0.670, 0.330) and demonstrated high colour purity (98.42 %) under excitation at 395 nm. Moreover, the phosphors Li3Ba2Gd3(WO4)8: Eu3+ exhibited favorable thermal stability, characterized by an activation energy of 0.219 eV. The aforementioned findings indicate that the phosphors Li3Ba2Gd3(WO4)8 doped with Eu3+ have the potential to function as a red-emitting phosphor in near-ultraviolet-driven white lightemitting diodes.