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The blue-emitting KBaYSi 2 O 7 :Bi3+ phosphor was prepared via the high-temperature solid-phase method, and the structural Si4+ was partially substituted by Al3+ and Ge4+ to improve its luminescence properties. A blue emission peak of the KBaYSi 2 O 7 :Bi3+ phosphor appears at 418 nm under an excitation of 370 nm, which is attributed to the 3P 1 →1S 0 electron transition of Bi3+. The luminescence intensity (λ em = 418 nm) of KBaYSi 1.94 Al 0.06 O 7 :0.03Bi3+ and KBaYSi 1.96 Ge 0.04 O 7 :0.03Bi3+ was 1.81 and 1.94 times that of KBaYSi 2 O 7 :0.03Bi3+, respectively. The luminescence intensity of phosphors at 423 K remained at 62.5 % (KBaYSi 1.94 Al 0.06 O 7 :0.03Bi3+) and 65.7 % (KBaYSi 1.96 Ge 0.04 O 7 :0.03Bi3+) of the initial values (at 303 K), respectively. The actual w -LEDs were fabricated with these blue-emitting phosphors, emitting a warm and bright white light. Therefore, the KBaYSi 2-x Al x O 7 :0.03Bi3+ and KBaYSi 2-y Ge y O 7 :0.03Bi3+ blue-emitting phosphors with excellent luminescence performance can be potential applied in w -LEDs and display fields. • Al3+ and Ge4+ substituted KBaYSi 2 O 7 :Bi3+ was first prepared for excellent blue emission. • The luminescence intensity of KBaYSi 2 O 7 :Bi3+ was enhanced by 1.81 and 1.94 times by Al3+ and Ge4+ substitution. • The combined w -LEDs with KBaYSi 2-x Al x O 7 :Bi3+ and KBaYSi 2-y Ge y O 7 :Bi3+emit a warm and bright white light. [ABSTRACT FROM AUTHOR]

To improve the luminescence property of Sm3+ in Y 2 Mo 3 O 12 , partial Ca2+-F- co-substituted Y 2 Mo 3 O 12 :Sm3+ phosphor, namely Y 2- x Ca x Mo 3 O 12- x F x :Sm3+, was prepared using a solid-state method. The effect of introducing Ca2+-F- ion pairs on structure and luminescence properties of Y 2 Mo 3 O 12 :Sm3+ was studied in depth. XRD patterns not only manifested that all as-prepared Y 2- x Ca x Mo 3 O 12- x F x :Sm3+ samples had standard Y 2 Mo 3 O 12 structure, but also indicated the introduction of Ca2+-F- ion pairs did not cause the change of crystal structure. Under the near ultraviolet excitation of 404 nm, the emission peaks of Y 2 Mo 3 O 12 :Sm3+ were located at 567 nm, 605 nm and 652 nm, respectively, resulting from the 4f→4f electron transitions of Sm3+ ions. Furthermore, the luminescence intensity of Sm3+ was obviously enhanced through the co-substitution of Y3+-O2- ions with Ca2+-F- ions in Y 2 Mo 3 O 12 structure, and the chromaticity coordinates moved towards red region, which due to the environmental effect of crystal field around Sm3+. Besides, the red LED device was manufactured for suitable chromaticity parameters. All results indicated that the as-prepared Y 1.84 Ca 0.06 Mo 3 O 11.94 F 0.06 :0.10Sm3+ red-emitting phosphor could become a promising candidate for application of white light-emitting diodes and plant illumination. [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]