Characterization and luminescence properties of a novel green emitting CaB2O4:Tb3+, Li+ phosphor

A series of novel metaborate phosphors CaB2O4:Tb3+,Li+ were successfully synthesized via the conventional solid-state reaction method. The crystal structures of the samples were characterized by powder X-ray diffraction and FT-IR spectrum. The excitation and emission spectra indicate that these phosphors can be effectively excited at 373 nm, and exhibit bright green emission centered at 548 nm due to the 5D4→7F5 transition of Tb3+. The effect of concentration of dopant ions on the luminescence was also studied. It reveals that the Tb3+ doping concentration in close proximity to 5 mol% is optimum, and the concentration quenching occurs when the Tb3+ ion concentration is beyond 5 mol%. The concentration quenching mechanism is demonstrated to be a dipole–quadrupole interaction, and the critical transfer distance was calculated to be about 14.34 Å. The experimental results show that this phosphor is a promising green-emitting phosphor pumped by near ultraviolet light.