Photoluminescence properties and thermal stability of blue-emitting Ba5-xCl(PO4)3:xEu2+ (0.004≤x≤0.016) phosphors.

A series of blue-emitting Ba5-xCl(PO4)3:xEu2+ (0.004≤x≤0.016) phosphors were synthesized by conventional high-temperature solid state reaction. The structure and photoluminescence (PL) properties of the phosphors were investigated. The as-prepared phosphors exhibit broad excitation band ranging from 250 to 420nm, and strong asymmetric blue emission band peaking at 436nm. The optimum concentration of Eu2+ in the Ba5Cl(PO4)3:Eu2+ phosphor is x=0.01, and the concentration quenching mechanism is verified to be the combined actions of dipole-dipole interaction and radiation re-absorption mechanism. The thermal stability of Ba5Cl(PO4)3:Eu2+ was evaluated by temperature-dependent PL spectra. Compared with that of commercial BaMgAl10O17:Eu2+ (BAM) phosphor, the Ba5-xCl(PO4)3:xEu2+ phosphors exhibit similarly excellent thermal quenching property. In addition, the CIE chromaticity coordinates of Ba5-xCl(PO4)3:xEu2+ (0.004≤x≤0.016) were calculated to evaluate the color quality. All the results indicate that Ba5Cl(PO4)3:Eu2+ is a promising candidate phosphor for near-ultraviolet (n-UV) pumped LED.