Abstract: A series of orange-red phosphors Sr3Ga2O5Cl2:Sm3+ are synthesized by the traditional high temperature solid-state method. The crystal structure of the sample is tested by X - ray diffraction (XRD), and its morphology and particle size are characterized by scanning electron microscopy (SEM). Photoluminescence spectra and decay lifetimes of the samples were measured using a fluorescence spectrometer. The crystal phase of Sr3Ga2O5Cl2 is monoclinic structure. Sm3+ ions replace Sr2+ sites to be the luminescence center of fluorescent powder. The excitation spectra of samples are composed of charge transfer band O2-→Sm3+ and characteristic excitation peaks of Sm3+ 4f inner-layer electrons, and the excitation peaks located at 230 nm and 404 nm are stronger. The peaks of emission spectra are located at 565, 601, 650 nm, which corresponds to the characteristic transition of Sm3+ from 4G5/2 level to 6H5/2, 6H7/2, 6H9/2 levels, respectively. The luminescent intensity of samples increases first and then decreases with the increasing of Sm3+ concentration, and the best doping concentration is 3.0% mol. Based on the experimental data, the reason of concentration quenching is discussed. The concentration quenching mechanism is electric dipole-dipole interaction.

Key words: luminescent materials; Sr3Ga2O5Cl2:Sm3+; phosphor; concentration quenching