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A series of Y2Mo4O15:Pr3+, Tb3+ red-emitting phosphors is synthesized via a solid-state reaction. The X-ray diffraction results indicate that the patterns of Y2Mo4O15:Pr3+, Tb3+ samples match well with the standard Y2Mo4O15 monoclinic structure. Under blue excitation at 453 nm, the Y2Mo4O15:Pr3+ phosphors show a red emission peaked at 614 nm, corresponding to the characteristic 1D2 → 3H4 electronic transition of Pr3+. Under near-ultraviolet excitation at 375 nm, the Y2Mo4O15:Tb3+ phosphor results in a double emission at 552 nm and 490 nm, which corresponding to the 5D4 → 7F5 and 5D4 → 7F6 electronic transitions of Tb3+. Furthermore, the luminescence properties of Y2Mo4O15:Pr3+ phosphor, especially luminescence intensity, was observably improved by the Tb3+ co-doping, which due to the emission peak of Tb3+ matches well with the excitation peak of Pr3+ at 490 nm and the resulted energy transfer between Tb3+ and Pr3+. The chromaticity coordinates of Y2Mo4O15:Pr3+, Tb3+ phosphors are all located in the red region. The results indicate that the prepared Y2Mo4O15:Pr3+, Tb3+ red phosphors are suitable for the applications of blue-excited warm white light-emitting diodes. [ABSTRACT FROM AUTHOR]

Orange–red-emitting phosphors Ca9La(VO4)7:Sm3+ and Ca9La(VO4)7:Sm3+,M+ (M+ = Li+, Na+, and K+) were synthesized by the combustion method. Their crystal structure, microstructure, luminescence properties, and decay performance were investigated in detail. The results revealed that the as-prepared samples were crystallized in a trigonal structure (space group of R3c, No. 161). Under 405-nm excitation, the Ca9La(VO4)7:Sm3+ phosphor exhibited excellent orange–red emission. The Sm3+ ions were quenched at 0.02 equivalents by electric dipole–dipole interactions. After the introduction of alkali metal ions Li+, Na+, and K+, the luminescence properties of the Ca9La(VO4)7:Sm3+ samples were noticeably enhanced, particularly those of that co-doped with Li+. The chromaticity coordinates of Ca9La(VO4)7:0.02Sm3+, 0.02Li+ and Ca9La(VO4)7:0.02Sm3+ were (0.610, 0.390) and (0.604, 0.395), respectively, close to those of the commercial red phosphor Y2O2S:Eu3+ (0.622, 0.351). The results suggested that the Ca9La(VO4)7:0.02Sm3+, 0.02Li+ phosphor may serve as an orange–red emitter for applications in white light-emitting diodes excited by near-ultraviolet radiation. [ABSTRACT FROM AUTHOR]

Dy3+-doped and Dy3+/Eu3+ co-doped NaBi(MoO4)2 phosphors were successfully synthesized using a high temperature solid-state method. The crystal structure and phase purity of these as-prepared samples were characterized by X-ray diffraction. Under 453 nm excitation, NaBi(MoO4)2:Dy3+ phosphors exhibited the characteristic weak blue emission peak at 488 nm and strong yellow emission peak at 577 nm, which originate from the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ ions, respectively. Therefore, a white light could be composed of a blue light from chip and yellow emission of NaBi(MoO4)2:Dy3+ phosphor. Additionally, color-tunable emissions were observed in the spectra of NaBi(MoO4)2:Dy3+, Eu3+ phosphors due to efficient energy transfer from Dy3+ to Eu3+ ions. By varying co-doping concentrations of Dy3+ and Eu3+ ions, the emission color of NaBi(MoO4)2:Dy3+, Eu3+ could be varied for high quality blue-excited white light-emitting diodes. [ABSTRACT FROM AUTHOR]

Dysprosium doped chlorapatite, Ca5(PO4)3Cl:Dy3+ white-emitting phosphors were synthesized by a solid-state reaction method. The effects of synthesis temperature, Dy3+ doping concentration, Eu3+ co-doping concentration and charge compensator Li+ co-doping on the crystal structures and luminescence properties of Ca5(PO4)3Cl:Dy3+ samples were investigated. Ca5(PO4)3Cl:Dy3+, Eu3+ and Ca5(PO4)3Cl:Dy3+, Li+ phosphors with standard Ca5(PO4)3Cl structure were prepared by heating above 900 °C, and the doped Dy3+, Eu3+/Li+ ions had no effect on the crystal structure. Under ultraviolet excitation at 366 nm, the emission spectra of Ca5(PO4)3Cl:Dy3+ phosphors exhibited two characteristic peaks of Dy3+ at 484 and 577 nm, which corresponding to the 4F9/2→6H15/2 and 4F9/2→6H13/2 electron transitions, respectively. Both blue and yellow emissions within a single-component host would constitute the white light. The white emission intensity of Ca5(PO4)3Cl:Dy3+ was enhanced markedly by Li+ co-doping as charge compensator. Moreover, Eu3+ co-doped Ca5(PO4)3Cl:Dy3+ phosphor showed an excellent warm white light with high chromaticity coordinates and low correlated color temperature though an additional red emission of Eu3+. The results indicate that these Ca5(PO4)3Cl:Dy3+, Eu3+/Li+ phosphors have potential applications in the field of white light-emitting diodes as single-component white-emitting phosphors. [ABSTRACT FROM AUTHOR]