Enhanced red emission from Eu3+–Bi3+ co-doped Ca2YSbO6 phosphors for white light-emitting diode

Abstract

Bi3+ and Eu3+ ions co-doped Ca2YSbO6 have been prepared via high temperature solid–state reaction. Its crystal structure and photoluminescence properties were investigated by X-ray diffraction patterns, diffuse reflection spectra, photoluminescence excitation and emission spectra. The results indicated that the Ca2YSbO6 crystallizes as a monoclinic structure with a space group of P21/n, with the lattice parameters related to that of the double perovskite by a = 5.5995 Å, b = 5.7964 Å, c = 8.0507 Å, α = γ = 90.00°, β = 89.8943°. The Ca2YSbO6:Eu3+ can be excited by ultraviolet, near-ultraviolet, and blue lights, and a strong red emission located at 614 nm (5D0→7F2) of Eu3+ ions was observed in all samples. By co-doping Bi3+ ions in Ca2YSbO6:Eu3+, the excitation band shifts to the long-wavelength region, and the red emission intensity was remarkably enhanced. With 5 mol% Bi3+ doped in Ca2YSbO6:Eu3+, the relative intensity of Ca2Y0.80Bi0.05Eu0.15SbO6 was enhanced by 327%, 389% and 348% excited at 290 nm, 400 nm and 470 nm compared with those of Ca2Y0.85Eu0.15SbO6, respectively. The composition-optimized Ca2Y0.8SbO6:0.15Eu3+, 0.05Bi3+ phosphor with strong red emission and good CIE chromaticity coordinate shows great potential for applications in white light-emitting diodes.