Photoluminescent enhancement by the incorporation of Bi³⁺ in Ba₂CaWO₆: Eu³⁺ phosphors

Abstract

A series of Bi³⁺-doped Ba₂CaWO₆: Eu³⁺ phosphors were prepared by the conventional high-temperature solid-state reaction method. The structure, composition and morphology of the prepared phosphor samples were analysed through XRD, XPS, EDS, FTIR, SEM and TEM analysis. Using the recorded photoluminescence excitation and emission profiles, the luminescence properties of Ba₂CaWO₆: Eu³⁺, Bi³⁺ phosphors were investigated thoroughly. Judd–Ofelt intensity parameters were also estimated from the emission spectra. An enhancement in emission intensity peaks was observed in the luminescence spectra of Ba₂CaWO₆: Eu³⁺ phosphors due to the incorporation of Bi³⁺ ions and the intense emission peak at 595 nm owes to the ⁵D₀ → ⁷F₁ magnetic dipole transition, thus confirming the occupancy of Eu³⁺ ion in the centrosymmetric site of Ba₂CaWO₆ matrix. Energy transfer from Bi³⁺ to Eu³⁺ ions occurred through the dipole–dipole interaction. The optimum doping concentration of Bi³⁺ is found to be 0.008 wt%. The co-doping of Bi³⁺ into Ba₂CaWO₆: Eu³⁺ matrix introduces a wide absorption band centred at 330 nm and a red shift from 314 to 330 nm. The decay profiles are well fitted with bi-exponential function. The efficient energy transfer from Bi³⁺ to Eu³⁺ ions within the Ba₂CaWO₆ matrix results in a strong reddish-orange emission from the prepared set of samples.