Novel yellowish-green emitting luminescence in Ca7Si2P2O16:Eu2+ phosphor

Color tunable green-origin-emitting phosphor of Eu2+-doped phosphate-silicate Ca7Si2P2O16 was prepared by chemical sol–gel method. The X-ray powder diffraction, the photoluminescence excitation and emission spectra, time resolved spectra, and thermal stability were measured. The excitation spectra can well match with the emission light of near UV-LED chips (360–400 nm). The tunable luminescence was realized by changing Eu2+-doping concentration. Ca7Si2P2O16:Eu2+ displays two typical luminescence centers, which were suggested to originate from two Ca2+ sites in the host. With increasing Eu2+ doping concentrations, the green emission band shifts to long wavelength. Energy transfer between the two different Eu2+ ions is discussed by analyzing the photoluminescence excitation and emission spectra, concentration-dependent luminescence intensity, and lifetimes. The dependence of the luminescence intensity of Ca7Si2P2O16:Eu2+ on temperatures was measured. The activation energy (ΔE) for thermal quenching was reported.