Synthesis and photoluminescence enhancement of Ca3Sr3(VO4)4:Eu3+ red phosphors by co-doping with La3+

Abstract In this study, a series of red-emitting Ca 3 Sr 3 (VO 4 ) 4 :Eu 3+ phosphors co-doped with La 3+ was prepared using the combustion method. The microstructures, morphologies, and photoluminescence properties of the phosphors were investigated. All Ca 3 Sr 3 (VO 4 ) 4 :Eu 3+ , La 3+ samples synthesized at temperatures greater than 700 ℃ exhibited the same standard rhombohedral structure of Ca 3 Sr 3 (VO 4 ) 4 . Furthermore, the Ca 3 Sr 3 (VO 4 ) 4 :Eu 3+ , La 3+ phosphor was effectively excited by near-ultraviolet light of 393 nm and blue light of 464 nm. The strong excitation peak at 464 nm corresponded to the 7 F 0 → 5 D 2 electron transition of Eu 3+ . The strong emission peak observed at 619 nm corresponded to the 5 D 0 → 7 F 2 electron transition of Eu 3+ . Co-doping with La 3+ significantly improved the emission intensity of Ca 3 Sr 3 (VO 4 ) 4 :Eu 3+ red phosphors. The optimum luminescence of the phosphor was observed at Eu 3+ and La 3+ concentrations of 5% and 6%, respectively. Moreover, co-doping with La 3+ also improved the fluorescence lifetime and thermal stability of the Ca 3 Sr 3 (VO 4 ) 4 :Eu 3+ phosphor. The CIE chromaticity coordinate of Ca 3 Sr 3 (VO 4 ) 4 :0.05Eu 3+ , 0.06La 3+ was closer to the NTSC standard for red phosphors than those of other commercial phosphors; moreover, it had greater color purity than that of all the samples tested. The red emission intensity of Ca 3 Sr 3 (VO 4 ) 4 :0.05Eu 3+ , 0.06La 3+ at 619 nm was ~1.53 times that of Ca 3 Sr 3 (VO 4 ) 4 :0.05Eu 3+ and 2.63 times that of SrS:Eu 2+ . The introduction of charge compensators could further increase the emission intensity of Ca 3 Sr 3 (VO 4 ) 4 :Eu 3+ , La 3+ red phosphors. The phosphors synthesized herein are promising red-emitting phosphors for applications in white light-emitting diodes under irradiation by blue chips.