Abstract
A series of efficient red light emitting Eu3+ activated LiGd(WO4)2 phosphors were prepared by solid state method at 800 °C. The PXRD Rietveld refinement results confirmed that all the compounds crystallized in the tetragonal structure with space group I41/a. All the samples showed the characteristic red emission of Eu3+ ions corresponding to the 5D0→7FJ (J = 0,1,2,3,4) transitions at λexc = 395 nm. The concentration quenching was observed above the LiGd(WO4)2:0.07Eu3+ due to charge exchange with neighbouring Eu3+ ions. The critical distance was determined to be about 16.05 Å indicates the multipole-multipole interaction. Judd–Ofelt theoretical analysis of the emission spectra are performed for Eu3+ activated LiGd(WO4)2 phosphors to evaluate the spectral characteristics and radiative properties. The observed trend of Judd–Ofelt intensity parameters Ω2 > Ω4 and domination of strong intense red emission (5D0→7F2) justify the asymmetric site occupancy of Eu3+ ions. In addition, the CL study also shows relative intensity and similar positions of characteristic emission band of rare earth ion as observed in PL spectra. Time resolved fluorescence spectra shows that decay curve is bi-exponential in nature and having lifetime (τ) 0.68 ms. The high color-purity red emission of the phosphor material with chromaticity co-ordinates (0.667, 0.332) in close proximity to that of commercial Y2O3:Eu3+ red phosphors with CIE co-ordinates (0.645, 0.347) corroborates the significance of LiGd(WO4)2:xEu3+ as efficient red emitters.
Published Version
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