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Transparent ceramics Y 3 Al 5 O 12 : Ce3+ (YAG: Ce) were prepared by the spark plasma sintering (SPS) process with B 2 O 3 acting as the sintering additive. The effect of B 2 O 3 on the microstructure and luminescent properties were examined. With the help of the liquid phase created by the low melting point B 2 O 3 additives, the carbon contamination of the SPS prepared YAG: Ce ceramics was remarkably relieved, the relative density and the in-line transmittance were enhanced, and the starting temperature of densification was lowered by approximately 170 °C. Moreover, the B 2 O 3 additive could enter into the YAG host lattice as a dopant. Consequently, the smaller B3+ ions replaced the Al3+ ions, enhancing the crystal field splitting of Ce3+ and significantly redshifting its 5d→4 f emission band. • YAG: Ce transparent ceramics were prepared by SPS using B 2 O 3 as additive. • The carbon contamination was greatly suppressed by B 2 O 3. • The relative density and the in-line transmittance of the ceramics were enhanced. • The emission band of Ce3+ was significantly redshifted by B 2 O 3. [ABSTRACT FROM AUTHOR]

Serial Bi3+/Mn4+ codoped double perovskite CaLaMgTaO6 phosphors were synthesized via a solid-state reaction method. When excited under 350 nm, CaLaMgTaO6: Bi3+, Mn4+ provided a blue emission band peaking at 440 nm due to the 3P1–1S0 transition of Bi3+ and a typical deep red emission band peaking at 699 nm owing to the 2Eg → 4A2 transition of Mn4+, which appropriately met the requirement of the growing plants for lighting. The ratio of the blue and deep red spectral component, as well as the emission color could be controlled by tuning the Bi3+/Mn4+ ratio. The energy transfer from Bi3+ to Mn4+ was investigated based on the photoluminescence spectra and fluorescence decay curves. The mechanism of energy transfer was demonstrated to be a dipole–dipole interaction. The quantum efficiency of Bi3+/Mn4+ codoped CaLaMgTaO6 phosphors are higher than that of Bi3+ or Mn4+ single-doped CaLaMgTaO6 phosphors thanks to the energy transfer process. [ABSTRACT FROM AUTHOR]

A novel Bi 3+ activated Ca 4 ZrGe 3 O 12 phosphor was synthesized and the photoluminescence properties were investigated. Ca 4 ZrGe 3 O 12 :Bi 3+ could be efficiently excited in the wavelength range of 320–430 nm, and exhibit a broad emission band (400–520 nm) with a peak at 435 nm corresponding to the 3 P 1 – 1 S 0 transition of Bi 3+ . Due to the energy transfer between Bi 3+ ions, the concentration quenching in the Ca 4 ZrGe 3 O 12 host occurred when the concentration of Bi 3+ exceeded 2.25 mol %. Upon excitation at 370 nm, the internal quantum efficiency of the phosphor with different Bi 3+ concentration was measured, the highest value was determined to be 38.6%. Moreover, the phosphor exhibited excellent thermal stability and the corresponding activation energy ΔE was determined to be 0.228 eV. Due to the efficient excitation in the near ultraviolet (n-UV) region and the strong blue emission, Ca 4 ZrGe 3 O 12 :Bi 3+ would be a potential blue phosphor for n-UV pumped light-emitting diodes. [ABSTRACT FROM AUTHOR]

Single-phased white light-emitting YNbO: Bi, Eu phosphors were synthesized by conventional solid-state reaction. YNbO: Bi phosphor exhibits a broad excitation band ranging from 220 to 360 nm and a blue light emission band peaking at 457 nm, originating from the P-S transition of Bi, whereas YNbO: Eu phosphor exhibits the typical red emission aroused from the D → F, D → F, D → F, D → F transitions of Eu. Under the excitation at 330 nm, the YNbO: Bi, Eu exhibits both the blue emission band of Bi and the red emission of Eu due to the energy transfer from Bi to Eu ions. By tuning the Bi/Eu ratio via the energy transfer, the emission hue of YNbO: Bi, Eu varied from blue (0.16, 0.18) to white (0.33, 0.24) and eventually to red (0.62, 0.33). The mechanism of energy transfer from a sensitizer Bi to an activator Eu in YNbO: Bi, Eu phosphors was demonstrated to be an exchange interaction. [ABSTRACT FROM AUTHOR]

Novel single-phase and color-tunable Ca 2 Y 3 Sb 3 O 14 : Bi 3+ , Eu 3+ phosphors were synthesized by conventional solid-state reaction. The obtained Ca 2 Y 3 Sb 3 O 14 : Bi 3+ phosphor exhibits a blue light emission band peaking at 460 nm due to the 3 P 1 – 1 S 0 transition of Bi 3+ , whereas Ca 2 Y 3 Sb 3 O 14 : Eu 3+ phosphor exhibits the typical red emission aroused from the 5 D 0 → 7 F J (J = 0, 1, 2) transitions of Eu 3+ . Due to the energy transfer from Bi 3+ to Eu 3+ ions, Ca 2 Y 3 Sb 3 O 14 : Bi 3+ , Eu 3+ exhibits both the blue emission of Bi 3+ and the red emission of Eu 3+ under 350 nm excitation. By tuning the Bi 3+ /Eu 3+ ratio, the emission color of Ca 2 Y 3 Sb 3 O 14 : Bi 3+ , Eu 3+ could vary from blue (0.16, 0.18) to red (0.62, 0.38), and white-light emission with superior CIE chromaticity coordinates (0.35, 0.30) and low correlated color temperature (CCT ≈ 3500 K) was obtained as a result of color tuning. The mechanism of energy transfer from the sensitizer Bi 3+ to the activator Eu 3+ in Ca 2 Y 3 Sb 3 O 14 : Bi 3+ , Eu 3+ phosphors was demonstrated to be an exchange interaction. [ABSTRACT FROM AUTHOR]

Highlights: [•] Sr12Al14O32Cl2:Eu2+ was synthesized by solid state reaction method. [•] Sr12Al14O32Cl2 crystallizes as a cubic structure with a space group of . [•] Sr12Al14O32Cl2:Eu2+ could be efficiently excited by near UV lights. [•] Sr12Al14O32Cl2:Eu2+ gives bright green emission band under near UV excitation. [ABSTRACT FROM AUTHOR]

Abstract A white light emitting diode (WLED) based on ZnO nanorods (ZNRs)/polymer blend p-n heterojunction has been fabricated. Different from the common commercial GaN WLEDs with a blue emission, the ZNRs/polymer blend WLED exhibits a blue-green emission peaked at 490 nm. Thus, the ZNRs/polymer blend WLED has a better cirtopic effect and smaller blue-light hazard. To get the 490 nm emission, intrinsic n-type ZNRs were annealed in a mixed gas of He and Zn vapor, and poly (9, 9-dioctylfluorene) (PFO) was mixed into the p-type polymer blend. Poly (3-hexylthiophene) (P3HT) was also mixed into the blends to get red emission. Results show the ZNRs/polymer blend heterojunction exhibits high-quality white-light emission with superior chromaticity coordinate (0.30, 0.33) as well as good cirtopic-effect spectrum. In comparison with the commercial GaN WLED, the ZNRs/polymer blend WLED is significantly potential for human health and work efficiency. Highlights • A white light emitting diode based on ZnO nanorods/polymer blend has been formed. • The new WLED exhibits a blue-green emission peaked at 490 nm. • The new WLED has a better cirtopic effect and smaller blue-light hazard. • The device shows high-quality white-light emission with superior chromaticity coordinate. [ABSTRACT FROM AUTHOR]

Bi 3+ and Eu 3+ ions co-doped Ca 2 YSbO 6 have been prepared via high temperature solid–state reaction. Its crystal structure and photoluminescence properties were investigated by X-ray diffraction patterns, diffuse reflection spectra, photoluminescence excitation and emission spectra. The results indicated that the Ca 2 YSbO 6 crystallizes as a monoclinic structure with a space group of P21/n, with the lattice parameters related to that of the double perovskite by a = 5.5995 Å, b = 5.7964 Å, c = 8.0507 Å, α = γ = 90.00°, β = 89.8943°. The Ca 2 YSbO 6 :Eu 3+ can be excited by ultraviolet, near-ultraviolet, and blue lights, and a strong red emission located at 614 nm ( 5 D 0 → 7 F 2 ) of Eu 3+ ions was observed in all samples. By co-doping Bi 3+ ions in Ca 2 YSbO 6 :Eu 3+ , the excitation band shifts to the long-wavelength region, and the red emission intensity was remarkably enhanced. With 5 mol% Bi 3+ doped in Ca 2 YSbO 6 :Eu 3+ , the relative intensity of Ca 2 Y 0.80 Bi 0.05 Eu 0.15 SbO 6 was enhanced by 327%, 389% and 348% excited at 290 nm, 400 nm and 470 nm compared with those of Ca 2 Y 0.85 Eu 0.15 SbO 6 , respectively. The composition-optimized Ca 2 Y 0.8 SbO 6 :0.15Eu 3+ , 0.05Bi 3+ phosphor with strong red emission and good CIE chromaticity coordinate shows great potential for applications in white light-emitting diodes. [ABSTRACT FROM AUTHOR]