Effect of photoluminescence property in Li+, Ca2+, Bi3+ ions co-doped SrMoO4:Eu3+ phosphors and their Judd–Ofelt analysis for solid-state lighting applications

Series of monovalent (Li + , Na + , K + ), divalent (Ca 2+ ) and trivalent (Bi 3+ ) ions co-doped with SrMoO 4 : Eu 3+ phosphors were synthesized by the conventional solid-state method. Rietveld refinement of XRD data reveals that the phosphors were crystallized in the scheelite type tetragonal structure with space group I4 1 /a . On substitution of Eu 3+ ion to Sr 2+ -site in SrMoO 4 host lattice, the photoluminescence spectra exhibit characteristic emission 5 D 0 → 7 F J ( J = 0–4) intra-4f shell of Eu 3+ ion transitions. PL spectra reveal that the observed electric dipole transition ( 5 D 0 → 7 F 2 , 616 nm) is more intense than the magnetic dipole transition ( 5 D 0 → 7 F 1 , 592 nm). Further, an enhanced the luminescent intensity by co-doping with the same cation charge with different ionic radii (Li + , Na + , K + ) and different cation charges, as well as ionic radii (Li + , Ca 2+ , Bi 3+ ) in Eu 3+ , activated SrMoO 4 host lattice. PL spectra reveals that, Li + ion co-doped phosphors exhibit 1.5 times more intense than SrMoO 4 : Eu 3+ phosphor due to the distorted nature of the local symmetry and charge compensation between dopant Eu 3+ and co-dopant Li + ions. The evaluated CIE 1931 color co-ordinates for Sr 0.14 Eu 0.11 Li 0.05 MoO 4 (0.648, 0.349) is very close to the commercial Y 2 O 3 :Eu 3+ (0.645, 0.347) and Y 2 O 2 S: Eu 3+ (0.647, 0.343) red phosphors. The determined Judd–Ofelt analysis and radiative properties suggest that the present phosphors have a long lifetime (0.527 ms), excellent color purity (92%), and a lower CCT value (2273 K). Hence, these classes of compounds are potential materials for the red component in developing white light-emitting diodes.