Design, synthesis and characterization of a novel yellow long-persistent phosphor: Ca2BO3Cl:Eu2+,Dy3+

A novel yellow emitting long-persistent phosphor Ca2BO3Cl:Eu2+,Dy3+ is developed. The incorporation of Dy3+ ions, which act as trap centers, largely extends the thermoluminescence characteristics and evidently enhances the persistent luminescence behavior of the phosphor. Both fluorescence and phosphorescence spectra of Ca2BO3Cl:Eu2+,Dy3+ reveal only one asymmetric broad emission band located at 580 nm, ascribed to the 5d–4f transitions of Eu2+ ions in two different sites. With the optimum doping concentration and sufficient excitation with UV light, the afterglow of samples can persist over 48 h above the recognizable intensity level (≥0.32 mcd m−2), a phenomenon that is infrequent and excellent. Furthermore, Ca2BO3Cl possesses an indirect bandgap of about 5.1 eV. Detailed processes and possible mechanism are studied and discussed.