Abstract
For the first time, a nano-scaled green-emitting Ba2Y5B5O17:Tb3+ nanophosphor series was prepared using an energy-efficient and simple solution combustion approach. A Rietveld refinement approach based on XRD was used to determine phase purity, crystalline structure, and lattice parameters of Ba2Y4.95Tb0.05B5O17 system. Doping of Tb3+ ion into an orthorhombic crystal lattice with Pbcn space group symmetry did not result in any significant structural alterations. A decrement in the energy bandgap was observed from 4.01 to 3.94 eV when Ba2Y5B5O17 host crystal lattice was doped with 0.05 mol of activator ions. PL spectra showed bright green emission at 544 nm (5D4 → 7F5) when excited with the near-ultraviolet photon. The Ba2Y4.95Tb0.05B5O17 composition produces the highest emission intensity. The critical distance of energy transfer assisted in identifying the correct mechanism (dipole–dipole) responsible for concentration quenching phenomena. Auzel’s model is used to compute the radiative lifespan (4.54 ms), non-radiative relaxation rate (77.355 s−1), and quantum efficiency (74%) of the lowest emitting 5D4 state in optimal phosphor composition. The electric-dipole radiative probabilities of transition (derived from overall radiative rates which include magnetic and electric-dipole) were employed to compute the intensity parameters Ωλ (λ = 2,4,6) = 0.76 × 10−20, 0.37 × 10−20 & 0.49 × 10−20 cm2 of Tb3+ ions in Ba2Y5B5O17 host lattice. The chromaticity coordinates revealing the green emission indicate the applicability of these Tb3+-doped Ba2Y5B5O17 nanophosphors as a primary green component in tricolor-based UV-excited WLEDs. Finally, the various optical results, including the calculated emission cross section of 5D4 → 7F5 transition also claim Ba2Y4.95B5O17:0.05Tb3+ system as a promising candidate for laser materials.