- 标题
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YAG:Ce <sup>3+</sup> Transparent Ceramic Phosphors Brighten the Next-Generation Laser-Driven Lighting
摘要： Y3Al5O12:Ce3+ (YAG:Ce3+) transparent ceramic phosphors (TCPs) are regarded as the most promising luminescent converter for laser-driven (LD) lighting. High-quality YAG:Ce3+ TCPs are still urgent for high efficiency LD lighting devices. YAG:Ce3+ TCPs in a vacuum ambience by using nano-sized raw materials are prepared. Controlling defects by adding nano-sized MgO and SiO2 simultaneously enables a high transmittance nearly 80%. After annealing in air furthermore, the luminous efficiency is enhanced greatly from 106 to 223 lm W?1, which is the best result reported now for LD lighting. These results demonstrate that the optimizing YAG:Ce3+ TCPs in a fitting strategy will brighten once again in the next-generation LD lighting. Based on scanning electron microscopy (SEM) coupled with a cathodoluminescence system, defects and Ce3+ distributions in grains are identified directly for the first time.
关键词： cathodoluminescence,laser-driven lighting,transparent ceramic phosphors,Mg2+–Si4+,YAG:Ce3+
更新于2025-09-23 15:21:01
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Luminescence properties and energy transfer investigations of Ce3+ singly doped and Ce3+/Tb3+ codoped Na3LuSi2O7 phosphors
摘要： The Na3LuSi2O7:Ce3+ and Na3LuSi2O7:Ce3+, Tb3+ phosphors were synthesized under a weak reducing atmosphere by the traditional high temperature solid state reaction method. The synthesized phosphors were characterized by X-ray diffraction (XRD), Photoluminescence (PL) emission and excitation spectra. The effects of Ce3+ singly doped and Ce3+/Tb3+ codoped concentrations on the structure, luminescence properties and energy transfer of Na3LuSi2O7 phosphors were studied in detail. The results indicated that the energy transfers between Ce3+ and Tb3+ in the host occurred mainly via a dipole-quadrupole mechanism, and the critical distances of the ion pairs (Rc) were calculated by the quenching concentration method and spectral overlap method. Based on the good PL properties adjusting the doping concentration of the activators (Ce3+,Tb3+) might be promising as a host material for solid-state lighting and display fields.
关键词： Luminescence,Na3LuSi2O7:Ce3+,Tb3+ phosphors,Energy transfer
更新于2025-09-19 17:15:36
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Ca(Mg <sub/>0.8</sub> Al <sub/>0.2</sub> )(Si <sub/>1.8</sub> Al <sub/>0.2</sub> )O <sub/>6</sub> :Ce <sup>3+</sup> ,Tb <sup>3+</sup> Phosphors: Structure Control, Density-Functional Theory Calculation, and Luminescence Property for pc-wLED Application
摘要： A modified structure Ca(Mg0.8Al0.2)(Si1.8Al0.2)O6 (denoted as CMASO) from the evolution of CaMgSi2O6 (denoted as CMSO) codoped with Ce3+ and Tb3+ ions was designed successfully by solid reaction method for application in phosphor-converted white-light-emitting diode (pc-wLED). The Rietveld refinement of these two structures verified the changes derived from the replacement of some of the Mg2+ and Si4+ ions by Al3+ ions. The band gaps were calculated by density-functional theory (DFT) calculation method to verify the change of Al3+ ions replacing further, and the diffuse reflectance spectra (DRS) proved the veracity of the calculation result. The phosphors CMASO:Ce3+ showed blue emission excited by a wider excitation wavelength from 280 nm to 370 nm. The change of structure lead to the absorbable range broaden and the emission peak shifted to longer wavelength, compared with CMSO:Ce3+, although the amount of emitting center was the same. The reason for these phenomena was discussed in detail. The codoped phosphors CMASO:Ce3+,Tb3+ exhibited different emission colors from blue to green as the concentration of Tb3+ ions increased. Combined with commercial red phosphor CaAlSiN3:Eu2+ and ultraviolet LED (UV-LED) chips, the selected appropriate samples achieved white emission. The correlated color temperature (CCT) was 6137 K and the color rendering index (Ra) was 80.5, indicating that they could act as potential phosphors for possible applications in pc-wLED.
关键词： Ce3+,pc-wLED,DFT,luminescence property,Tb3+,Ca(Mg0.8Al0.2)(Si1.8Al0.2)O6,phosphor-converted white-light-emitting diode,density-functional theory
更新于2025-09-19 17:13:59
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Highly efficient near-UV-excitable Ca2YHf2Al3O12:Ce3+,Tb3+ green-emitting garnet phosphors with potential application in high color rendering warm-white LEDs
摘要： Inorganic phosphors with broadband near-ultraviolet (near-UV) excitation and efficient visible emissions are highly important for fabricating high-performance near-UV-pumped white light-emitting diodes (LEDs). Herein, we reported on novel efficient near-UV-excitable Ce3+/Tb3+ ions co-activated Ca2YHf2Al3O12 (CYHA) green-emitting garnet phosphors, which were successfully prepared through a high-temperature solid-state reaction process. X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, elemental mapping, photoluminescence, CIE color coordinates, internal and external quantum efficiency, and temperature-dependent emission spectra were used to characterize the samples. Interestingly, due to the efficient energy transfer from Ce3+ to Tb3+ ions in CYHA, the CYHA:Ce3+,Tb3+ samples presented a wide excitation band in the 370-470 nm region peaking around 408 nm owing to the 4f-5d transition of Ce3+ ions, and under 408 nm excitation they showed intense characteristic sharp green emissions around 543 nm corresponding to the 5D4→7F0-6 transitions of Tb3+ ions. The energy transfer mechanism from Ce3+ to Tb3+ ions was ascribed to the quadruple-quadruple interaction, and the energy transfer efficiency reached as high as 93.2%. Notably, the composition-optimized CYHA:0.03Ce3+,0.6Tb3+ sample exhibited high internal quantum efficiency (IQE) of 78.5% and external quantum efficiency (EQE) of 56%, which were much higher than those of the Tb3+ singly-activated CYHA:0.6Tb3+ sample (IQE = 8%, EQE = 2.2%). Finally, a prototype white LED device was made by combining a 400 nm near-UV-emitting LED chip with the phosphor blend of the as-prepared CYHA:0.03Ce3+,0.6Tb3+ green phosphors, commercial BaMgAl10O17:Eu2+ blue phosphors and commercial CaAlSiN3:Eu2+ red phosphors, which emitted bright warm-white light with good CIE chromaticity coordinates of (0.391, 0.356), low correlated color temperature of 3528 K and high color rendering index of 92.3 under 120 mA driven current. This work opens up new opportunities for the development of efficient color converters toward near-UV-pumped warm-white LEDs with high color rendering index.
关键词： white LEDs,green-emitting garnet phosphors,Ce3+/Tb3+ co-activated,near-UV-excitable,energy transfer
更新于2025-09-19 17:13:59
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Efficient green-emitting Ca2GdZr2Al3O12:Ce3+,Tb3+ phosphors for near-UV-pumped high-CRI warm-white LEDs
摘要： In this work, we reported novel efficient Ce3+/Tb3+ co-doped Ca2GdZr2Al3O12 (CGZA) green-emitting phosphors by traditional solid state method. The phase purity, crystal structure, morphology, photoluminescence properties, internal quantum efficiencies (IQEs), and thermal stability of the samples were systematically investigated. The obtained results revealed that there was an obvious spectral overlap between the emission spectrum of Ce3+ singly doped CGZA phosphors and excitation spectrum of Tb3+ singly doped CGZA phosphors, and efficient energy transfer from Ce3+ to Tb3+ ions existed in Ce3+ and Tb3+ co-doped CGZA phosphors. The Ce3+→Tb3+ energy transfer mechanism was ascribed to the dipole-dipole interaction. The CGZA:Ce3+,Tb3+ phosphors exhibited a broad excitation spectrum in the wavelength range of 370-470 nm with a maximum at 408 nm corresponding to the spin-allowed 4f-5d transition of Ce3+ ions. Upon near-ultraviolet (near-UV) excitation at 408 nm, the composition-optimized CGZA:0.02Ce3+,0.8Tb3+ sample showed intense sharp narrow-line emissions at 485, 543, 591, 629, 643, 663, and 679 nm due to the 5D4→7FJ (J = 6-0) transitions of Tb3+ ions, along with a good IQE of 51%. Lastly, a white LED device was fabricated by using as-prepared CGZA:0.02Ce3+,0.8Tb3+ green phosphors, commercial BaMgAl10O17:Eu2+ blue phosphors, and CaAlSiN3:Eu2+ red phosphors, and under 300 mA driven current it gave bright warm-white light with a low correlated color temperature of 3969 K and a high color rendering index (Ra = 91.2). Our work provides a new perspective for the design and fabrication of efficient color conversion materials toward near-UV LED-based warm-white LEDs.
关键词： Garnet,Ce3+ ions,White LEDs,Phosphors,Tb3+ ions,Photoluminescence
更新于2025-09-16 10:30:52
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Closing the Cyan-Gap toward Full Spectrum LED Lighting with NaMgBO3:Ce3+
摘要： The photoluminescence spectrum generated by an ordinary phosphor-converted white light-emitting diode (pc-wLED) that combines a blue LED chip with a yellow phosphor or a near-UV LED with red, green and blue phosphors contains a notable cavity in the cyan region of the visible spectrum (480-520 nm) that reduces the color quality produced by these lights. Here, we report a new bright blue-cyan-emitting phosphor, NaMgBO3:Ce3+, that bridges the gap. Rietveld refinements verify the rare-earth substitution while ab initio calculations prove Ce3+ occupies the Na+ sites. NaMgBO3:Ce3+ is excited by a broad range of near-UV light sources and produces a blue-cyan emission with a high (internal) quantum efficiency, minimal thermal degradation, and zero-chromaticity drift at elevated temperatures. Fabricating a near-UV (λex = 370 nm) pumped pc-wLED using NaMgBO3:Ce3+ along with commercially available phosphors demonstrates a well-distributed warm white light with a high color-rendering index (Ra) of 91 and a low correlated color temperature (CCT) of 3645 K. Closing the cyan cavity with NaMgBO3:Ce3+ is ideal for generating a pleasant, full-spectrum, warm white light.
关键词： full-spectrum LED lighting,NaMgBO3:Ce3+,blue-cyan-emitting phosphor,color-rendering index,phosphor-converted white light-emitting diode
更新于2025-09-12 10:27:22
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Phase transformation and luminescence properties of Y2.94Al5-xGaxO12: 0.06Ce3+phosphors
摘要： A series of Ga-substituted Ce3+-doped yttrium aluminum garnet (Y2.94Al5-xGaxO12: 0.06Ce3+) phosphors were synthesized at different atmospheres and temperatures. The structure, optical and thermal stability properties were analyzed using X-ray diffraction (XRD), photoluminescence (PL) and thermal measurements. A novel finding was revealed that gallium oxide (Ga2O3) was unstable in reducing atmosphere by XRD, and we explained the mechanism for the first time. In addition, it was found that Y3Al3Ga2O12 was formed due to Al3+ ions entering the lattice of Y3Ga5O12 gradually and the mechanism was clearly illustrated. The emission intensity of Y2.94Al5-xGaxO12: 0.06Ce3+ phosphors was determined by two aspects—the phase formation temperature and the band gap of host lattice. What’s more, introducing 6 wt% H3BO3 as flux can improve thermal stability to maximum extent and the thermal ionization model was used to explain the thermal quenching mechanism. Finally, the critical parameters including color rendering index (CRI), correlated color temperature (CCT), light efficiency of light emitting diodes (LEDs) packaged with the resultant green phosphors and red phosphors were studied.
关键词： thermal ionization,band gap,YAGG: Ce3+,phase transformation
更新于2025-09-10 09:29:36
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Crystal Growth and Scintillation Properties of YAG:Ce3+ for γ and α Detection
摘要： A bulk single crystal of yttrium aluminum garnet (Y3Al5O12:Ce3+, YAG:Ce3+) with good optical quality and free of cracks has been grown successfully by the Kyropoulos method. The dimension of the as grown crystal boule was ? 20 × 30 cm3. The cut and polished crystal sample of dimensions 1 × 1 × 0.5 cm3 was used for further measurements. The phase purity was confirmed by powder X-ray diffraction pattern analysis. The scintillation properties, such as X-ray emission spectrum, pulse height spectra, energy resolution, and scintillation decay time, were investigated using a 137Cs γ-ray source. The recorded X-ray emission spectrum shows a broad band between 500 and 700 nm with a peak at around 540 nm, which is attributed to the 5d-4f transition of the Ce3+ ion. The pulse-shape discrimination (PSD) of α and γ signals in a YAG:Ce3+ crystal has been studied by using different pulse shapes. The grown YAG:Ce3+ crystal which is non-hygroscopic, chemically inert, fast inorganic scintillator could be used for radiation detection application in nuclear, and high energy physics.
关键词： YAG:Ce3+ crystal,Kyropoulos method,Pulse shape discrimination,Radiation detector
更新于2025-09-09 09:28:46