Structural and luminescence properties of Dy3+ doped bismuth phosphate glasses for greenish yellow light applications

Abstract Different compositions of (5, 10, 15 and 20 mol%) of bismuth and different concentrations (0.5, 1.0, 1.5 and 2.0 mol%) of Dy 3+ ion doped bismuth phosphate (BiP) glasses were synthesized by melt-quenching technique. The structural characterization was accomplished by XRD, SEM with EDS, FTIR, FT-Raman and 31 P MAS NMR spectroscopy. The optical properties were studied using absorption and photoluminescence spectroscopy. Different structural groups were identified using FTIR and FT-Raman spectra. The depolymerization of metaphosphate chains are described by the decrease of Q 2 tetrahedral sites allowing the formation of pyrophosphate groups (Q 1 ) revealed by 31 P MAS NMR spectroscopic investigations. Judd-Ofelt intensity parameters Ω λ (λ = 2, 4 and 6) were evaluated from absorption spectra. Radiative parameters such as radiative lifetimes (τ R ), integrated absorption cross-sections (Σ) and branching ratios (β R ) were calculated using Judd-Ofelt intensity parameters. From photoluminescence spectra, experimental branching ratios (β exp ) and stimulated emission cross-sections (σ P ) were calculated for all the observed emission transitions of prepared glasses. The decay profiles for 4 F 9/2 level were recorded and fit exponential for 0.5 mol% and non-exponential for higher concentrations of Dy 3+ due to non-radiative energy transfer among excited Dy 3+ ions. The CIE chromaticity co-ordinates have been calculated from the luminescence spectra which confirmed greenish yellow light emission.