白光LED用新型绿色荧光粉Ca5(SiO4)2F2:Eu(上标 2+)的发光性能

A series of new green-emitting phosphors, Eu(superscript 2+)-activated Ca(subscript 5-x)Eu(subscript x) (SiO4)2F2 were synthesized at 1223 K by conventional high-temperature solid-state reactions under reductive atmosphere. And the photoluminescence excitation, diffuse reflectance and emission spectra, concentration quenching process, temperature dependence of luminescence and lifetime of phosphors were systematically investigated. The excitation spectrum shows that Ca5 (SiO4)2F2:Eu(superscript 2+) can be efficiently excited by the incident lights of 250~440 nm, perfectly matching with the emissions wavelength of near-UV LEDs. The emission intensity is influenced by the Eu(superscript 2+) content, and the optimal doping mole fraction is about 0.15. The concentration quenching mechanism was verified as dipole-dipole interaction and the value of the critical transfer distance was calculated as 1.5 nm. The temperature dependent emission spectra in the temperature range of 10~450 K show that the emission intensity at 450 K is 35% of the emission intensity at 10 K. At room temperature, the lifetimes of Eu(superscript 2+) ions in Ca4.85Eu0.15(SiO4)2F2 phosphors are determined to be 1.78 μs and 7.79 μs, respectively. All of these indicate that Ca5(SiO4)2F2:Eu(superscript 2+) is a promising green phosphor candidate for phosphor-converted white LEDs.