Color centers and dynamic emission of Eu2+ ion doped halosilicate Ca10Si6O21Cl2

Rare earth (Eu2+) ion doped halosilicate Ca10Si6O21Cl2 was prepared by a solid state reaction method. The X-ray powder diffraction patterns, the scanning electron micrographs, the photoluminescence excitation and emission spectra, and the thermal stability were measured. The luminescence properties were investigated by dynamic excitation of a pulsed UV laser. Two typical Eu2+ emission centers were suggested from two different Ca2+ cation sites in the lattice. With increasing Eu2+-doping concentration, energy transfer between the two Eu2+ centers can happen. The emission mechanism is discussed by analyzing the excitation and emission spectra, the concentration-dependent luminescence intensity, and the lifetimes. The colors of Ca10Si6O21Cl2:Eu2+ change from bluish green to yellowish green by increasing the Eu2+-doping concentration. The luminescence stability with temperature was evaluated by the activation energy for thermal quenching.