Novel reddish-orange emitting BaBPO5:Eu3+ phosphor for n-UV warm white-LEDs: Synthesis and study of structural and spectroscopic investigations

A novel reddish-orange emitting 2Ba_2-xO-B₂O₃-P₂O₅:xEu³⁺ (x= 0.04, 0.06, 0.08, 0.10, 0.12 and 0.14 mol%) phosphor with different concentrations of Eu³⁺ ions were synthesized through high temperature solid-state reaction technique. The crystal structure has been studied by X-ray diffraction technique for all the concentrations of Eu³⁺ ions. The morphology and elemental analysis of the optimal ∼0.1 mol% concentration was examined by the SEM-EDS images. The functional groups were analysed by the FTIR characterization technique. The thermal properties were studied by the TGA-DSC analysis. The energy band gap of all the samples were analysed by using UV–VIS DRS technique. The photoluminescence properties of BaBPO₅:Eu³⁺ phosphor with different concentrations of Eu³⁺ ions were investigated at λ_em = 611 nm and λ_ex = 394 nm. Variation in emission intensity with Eu³⁺ ion concentrations, phonon side bands, multi-phonon relaxation rate and energy transfer mechanisms were studied. The BaBPO₅:Eu³⁺ phosphors exhibit characteristic emission peaks corresponding to ⁵D₀ → ⁷F_J (J = 0, 1, 2, 3, 4) transitions of Eu³⁺ ions under n-UV excitation. Among all the transitions, ⁵D₀ → ⁷F₁ (593 nm) transition shows higher intensity and asymmetric ratio (R₂₁) for all concentrations of Eu³⁺ ions were calculated. The lifetimes of ⁵D₀ level of Eu³⁺ ions in BaBPO₅: Eu³⁺ phosphor were calculated by using fluorescent decay curve analysis. The CIE color coordinates reveal, reddish-orange emission in the low CCT range. These findings imply that BaBPO₅: 0.1Eu³⁺ phosphor is a promising candidate for solid-state lighting applications as well as phosphor-converted warm w-LEDs.