The concentration quenching and crystallographic sites of Eu2+in Ca2BO3Cl

A yellow phosphor, Ca2BO3Cl:Eu2+, is prepared by the high-temperature solid-state method. Under the condition of excitation sources ranging from ultraviolet to visible light, efficient yellow emission can be observed. The emission spectrum shows an asymmetrical single intensive band centred at 573 nm, which corresponds to the 4f65d1→4f7 transition of Eu2+. Eu2+ ions occupy two types of Ca2+ sites in the Ca2BO3Cl lattice and form two corresponding emission centres, respectively, which lead to the asymmetrical emission of Eu2+ in Ca2BO3Cl. The emission intensity of Eu2+ in Ca2BO3Cl is influenced by the Eu2+ doping concentration. Concentration quenching is discovered, and its mechanism is verified to be a dipole—dipole interaction. The value of the critical transfer distance is calculated to be 2.166 nm, which is in good agreement with the 2.120 nm value derived from the experimental data.