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

Abstract

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.