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Eu3+ activated red phosphors based on the CaY x (MoO 4) 1.5x+1 (x = 0.2, 0.4, 0.6, 1, 2) as host materials were synthesized by using a combustion method. XRD analysis demonstrated that the synthesized samples matched with the standard card CaMoO 4 (JCPDS NO.77-2239) belonging to the tetragonal of the I4 1 /a space group. All samples showed several narrow sharp emission peaks under 393 nm n-UV excitation, the strongest of which was at 618 nm attributed to the 5D 0 →7F 2 transition of Eu3+. The optimal composition of the host was found to be CaY 0.6 (MoO 4) 1.9 (hereafter referred to as CYMO). After doping Sm3+ into CYMO:Eu3+ phosphor, the absorption peaks of Eu3+ at 393 and 464 nm were broadened, and the peak intensity was also significantly higher than that of single-doped Eu3+. The energy transfer phenomenon between Sm3+ and Eu3+ was discovered by the excitation and emission spectra in CYMO:Eu3+,Sm3+ phosphors, and verified by the fluorescence lifetime of Sm3+ ions in the phosphors. The energy transfer mechanism between Sm3+ and Eu3+ is a dipole-dipole interaction, where the energy transfer efficiency in CYMO phosphor doped with 13% Eu3+ and 3% Sm3+ is 17.9%. The CIE coordinate and color purity were calculated as (x = 0.6598, y = 0.3388) and 93.72%, which indicated that the CYMO:13%Eu3+,3%Sm3+ phosphor is a red phosphor with excellent performance for potential application in n-UV light excited w-LEDs. [ABSTRACT FROM AUTHOR]

In this study, a series of white light-emitting NaSrVO 4 :Dy3+ phosphors with La3+ co-doping were produced by a combustion method. The configurations of the as-prepared NaSrVO 4 :Dy3+ and NaSrVO 4 :Dy3+, La3+ specimens are consistent with the standard phase of NaSrVO 4. The impacts of the Dy3+ concentration and La3+ co-doping on the luminescence characteristics of NaSrVO 4 : Dy3+ phosphors were explored. The specimens excited by near-ultraviolet light displayed emission peaks at 580 (yellow) and 484 nm (blue), which were ascribed to the 4F 9/2 → 6H 13/2 and 4F 9/2 → 6H 15/2 transitions of the Dy3+ ions, respectively. The white light was manufactured by these two emissions from the NaSrVO 4 : Dy3+ phosphor. Photoluminescence studies demonstrated that the La3+ co-doping efficiently improved the luminescence characteristics of the NaSrVO 4 : Dy3+ phosphor. These results suggest that the NaSr 0.9425 VO 4 : 0.05Dy3+, 0.0075La3+ phosphors excited by near-ultraviolet are promising materials for white light-emitting diodes. [ABSTRACT FROM AUTHOR]

A series of β -Ca 3 (PO 4) 2 type single-component Ca 19 Zn 2 (PO 4) 14 :Dy3+, M+ (M = Li, Na and K) white-emitting phosphors were synthesized via a high-temperature solid-state reaction method, where alkali metal ions (M+) co-doped as charge compensator into the Ca 19 Zn 2 (PO 4) 14 :Dy3+ phosphor was aimed at improving the overall luminescence. The influences of synthesis temperature and the M+ introduction on both structure and luminescence property were thoroughly studied. X-ray diffraction patterns verify that the as-prepared phosphors attain the standard Ca 19 Zn 2 (PO 4) 14 phase without impurities. Photoluminescence peaks at 484 nm and 575 nm (originating from the 4F 9/2 → 6H 15/2 and 4F 9/2 → 6H 13/2 electron transitions of Dy3+ ions) were produced for all samples with an excitation of 386 nm, which then combined to emit white light. The luminescence intensities of Ca 19 Zn 2 (PO 4) 14 :Dy3+ were dramatically improved through co-doping with M+ into the phosphor structure. These results demonstrate the promising application prospects of Ca 19 Zn 2 (PO 4) 14 :Dy3+, M+ white-emitting phosphors in white light-emitting diodes. [ABSTRACT FROM AUTHOR]

A novel white emitting phosphate-based phosphor Ca 3- x Li x (PO 4) 2- x (SO 4) x :Dy3+, Sm3+ with high emission intensity and lower correlated color temperature were successfully synthesized via the sol-gel method. The structures of these prepared phosphors matched well with standard Ca 3 (PO 4) 2. The Dy3+-doped Ca 3- x Li x (PO 4) 2- x (SO 4) x phosphors showed white luminescence via the combination of blue (487 nm) and yellow (578 nm) emissions, which were attributed to the 4F 9/2 → 6H 15/2 and 4F 9/2 → 6H 13/2 electron transitions of Dy3+, respectively. The synthesized phosphor exhibited a significant enhancement in luminescence intensity at the optimum value of x = 0.15. With the incorporation of Sm3+, a warm white emission with lower correlated color temperature (4281 K) was achieved in Dy3+/Sm3+ co-doped samples. The obtained external quantum efficiency reached 21.7% in the optimized phosphor. The improved performance was strongly associated with red emission supplemented by Sm3+, and it demonstrated the existence of efficient energy transfer between the Dy3+ and Sm3+ ions (4F 9/2 → 4G 7/2 and 4F 9/2 → 4G 5/2). Overall, the investigation carried out by us has revealed that the luminescence properties of Ca 3 (PO 4) 2 phosphor can be significantly improved through Li+/S6+ partial substitution and Dy3+/Sm3+ co-doping. Image 1 • A novel Li+/S6+ co-substituted Ca 3 (PO 4) 2 :Dy3+ white-emitting phosphor was prepared. • Ca2+/P5+ couples were partially substituted with Li+/S6+ for luminescence enhancement. • A white light could be realized with a blue emission and yellow emission of Ca 3- x Li x (PO 4) 2- x (SO 4) x :Dy3+. • Warm white emission with low CCT can be achieved for Ca 2 · 85 Li 0 · 15 (PO 4) 1 · 85 (SO 4) 0.15 :Dy3+ phosphor by Sm3+ ions co-doping. [ABSTRACT FROM AUTHOR]