The asymmetry of the local environment within host materials plays a critical role in enhancing the emission performance of Eu3+ ions. In this study, we introduced a novel Si4+-doping strategy to optimize the luminous properties of Eu3+ ions by promoting asymmetry in the local lattice environment. And then, a series of Si4+/Eu3+ co-doped Sr3Ga2Ge4O14 phosphors were synthesized. Our findings reveal that Si4+-doping at a concentration of 60 mol% significantly enhances the emission intensity of Eu3+ ions in the Sr3Ga2Ge4O14 host by approximately 80%. Also, the internal quantum efficiency increases from 37.80% to 49.04%, alongside a rise in color purity from 87.40% to 99.80%. Utilizing this Sr2.3Ga2Ge1.6Si2.4O14:0.7Eu3+ high-performance red phosphor, we fabricated a white light-emitting diode (WLED) device with natural white light characteristics, achieving CIE coordinates of (0.338, 0.323), a correlated color temperature (CCT) of 5636 K, and a color rendering index (CRI) of Ra = 89.4. Additionally, we developed a high-performance anti-counterfeiting ink using this red phosphor, which adheres uniformly to surfaces with varying roughness and delivers exceptional luminescence effects. This study provides new insights into the development of advanced red-emitting phosphors for applications in lighting and anti-counterfeiting technologies.
Wenlei Liu,Jianxing Shen,Qingle Pang,Tailin Wang,Xiujun Han
Cerium-doped yttrium aluminum garnet (YAG:Ce) based transparent ceramics have been widely used in fluorescent lighting as high-quality inorganic fluorescent conversion materials. This paper further explores the Mg 2+ -Si 4+ ions doped YAG:Ce transparent ceramics by combining the solid-phase reaction method with vacuum hot-pressure sintering and implementing protection measures against hot-pressure mold contamination, and also investigates the effect of different Mg 2+ -Si 4+ doping contents on the structure, transmittance and luminescence properties of the ceramics under hot-pressure sintering. In this work, pure-phase YMASG:Ce transparent fluorescent ceramics with a grain size of about 3-6 μm and clear and clean grain boundaries were obtained with an In-line transmittance of 67% at 800 nm. Under the excitation at 460 nm, the emission peak was red-shifted by 26 nm and the full width at half maxima (FWHM) was broadened with the increase of Mg 2+ -Si 4+ content, which shows that the Mg 2+ -Si 4+ ion pair effectively complements the absence of the red light component in the YAG:Ce emission spectrum. The optimized YMASG:Ce ceramics obtained high-quality warm white light with a low correlated color temperature (CCT) and a high color rendering index (CRI) under the excitation of the blue LED chip. This work proved the feasibility of vacuum hot-pressure sintering to prepare YMASG:Ce transparent fluorescent ceramics, and provided a new approach for studying YMASG:Ce-based ceramics, which was significant for the application of high-power visible laser illumination.
Qinghong Meng,Guoying Zhao,Qi Zhu,Xudong Sun,Ji-Guang Li
Doping Gd2LuAl5O12:Ce with a Ca2+/Si4+ pair produced a series of Gd1.97−xLuCaxAl5−xSixO12:0.03Ce (x = 0.0–1.2) garnet new phosphors, and remarkable regulation of the crystal structure and Ce3+ luminescence was achieved. Rietveld refinement and spectral analysis revealed that greater incorporation of Ca2+/Si4+ led to a higher lattice rigidity by cell contraction, a narrower bandgap, a longer average bond length/less distortion of the [CeO8] dodecahedron and decreased centroid shift/crystal field splitting of the Ce3+ 5d energy level. A blue-shifted 4f–5d1 transition, a narrower emission band, improved thermal stability of luminescence and a shorter fluorescence lifetime were observed with increasing Ca2+/Si4+ content. Applying the yellowish-green-emitting Gd0.77LuCa1.2Al3.8Si1.2O12:0.03Ce optimal phosphor (x = 1.2), together with a commercial CaAlSiN3:Eu red phosphor, in 450 nm-excited LED lighting produced a low CCT of ∼3625 K and a high CRI/R9 of ∼95.2/94.8, indicating that the phosphor has application potential in high-performance w-WLED.
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