Turning on the luminescence of Sr5(PO4)3Cl: Eu2+ by doping of La, Gd and Lu ions for full-spectrum lighting application

Blue phosphor Sr 5−x-y R y (PO 4 ) 3 Cl:xEu 2+ (R = La, Gd, Lu) was prepared via solid-state reaction process, in which R 3+ replaces part of Sr 2+ ions in the matrix to benefit Eu 2+ luminescence. The change of Eu 2+ /Eu 3+ values were studied by XPS , and the results shown that the incorporation of R 3+ in the matrix resulted in the values increase of Eu 2+ /Eu 3+ . And substitute R 3+ non-equivalently for Sr 2+ , the modified Sr 5−x-y R y (PO 4 ) 3 Cl:xEu 2+ phosphors show better luminescence intensity and thermal stability. The emission intensity of Sr 4.72 Lu 0.2 (PO 4 ) 3 Cl:0.08Eu 2+ is 1.97 times of Sr 4.95 (PO 4 ) 3 Cl:0.05Eu 2+ . Moreover, the thermal quenching of Eu 2+ photoluminescence could be reduced. Compared to the commercial BAM:Eu 2+ phosphor, the stabilities of all Sr 4.72 R 0.2 (PO 4 ) 3 Cl:0.08Eu 2+ (R=La 3+ , Gd 3+ and Lu 3+ ) phosphors are better than that of BAM:Eu 2+ at the temperatures below 100 °C. The luminescent intensity of Sr 4.72 Lu 0.2 (PO 4 ) 3 Cl:0.08Eu 2+ maintains 95% while BAM:Eu 2+ is only 88% of the initial intensity at 150 °C. By combining Sr 4.72 Lu 0.2 (PO 4 ) 3 Cl:0.08Eu 2+ , Y 3 (Al,Ga) 5 O 12 :Ce 3+ and CaAlSiN 3 :Eu 2+ with 400 nm near-ultraviolet LED chip, a white-light-emitting diode was obtained. The fabricated WLED device with CIE color coordinates x  = 0.3896, y  = 0.3788, low CCT (3775 K) and high Ra (95.1), has enormous potential application in full-spectrum lighting field.