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

• Blue Ba5 − xCl(PO4)3:xEu2 + phosphors were prepared at low temperature of 875 °C.
• The broad excitation band of the phosphor matches well with n-UV LED chips.
• The phosphor possesses excellent thermal quenching stability similar to BAM.
• Two mechanisms were verified to cause concentration quenching of Eu2 +.

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 420 nm, and strong asymmetric blue emission band peaking at 436 nm. 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.

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