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Luminescence of monoclinic Y2O3:Eu nanophosphor produced via laser vaporization
摘要： Europium doped Y2O3spherical nanoparticles with the diameter ~10 nmobtained via cw laser vaporization are shown to crystallize in monoclinic symmetry class (C2/m space group). The size of nanoparticles established via HRTEM coincides with coherent scattering region established by XRD. Luminescence spectrum in the vicinity of ultranarrow transition demonstrates three peaks consistent with three inequivalent positions of Eu3t ion in monoclinic Y2O3 lattice. Hypersensitive transition dominates in the spectrum, admitting the lack of inversion symmetry at Cs sites occupied by Eu3t. The spectrum of hypersensitive transition is expanded to the red part of spectrum due intense transitions terminating at higher-lying components of crystal-field-split 7F2 energy level. Obtaining chromaticity coordinates (0.669, 0.331)and absolute quantum yield (~21%) is possible using red phosphor based on monoclinic Y2O3:Eu3t.
关键词： Laser vaporization,Monoclinic Y2O3:Eu nanophosphor,Photoluminescence of Eu3t
更新于2025-09-23 15:21:01
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Realizing bright blue-red color-tunable emissions from Gd2GeO5:Bi3+,Eu3+ phosphors through energy transfer toward light-emitting diodes
摘要： Novel Bi3t, Eu3t co-doped Gd2GeO5 (GGO) phosphors were prepared by a high-temperature solid-state reaction method. X-ray diffraction, photoluminescence (PL), CIE chromaticity coordinates, internal quantum efficiency (IQE), and temperature-dependent PL spectra were applied to analyze the as-obtained phosphors. The emission spectra of the GGO:Bi3t, Eu3t phosphors showed both a broad blue band of Bi3t ions emission centered at 453 nm and the characteristic sharp red emission lines of Eu3t ions, corresponding to the 3P1→1S0 allowed transition of the Bi3t ions and the 5D0→7FJ (J ? 0, 1, 2, 3, 4) transitions of the Eu3t ions, respectively. Notably, the as-prepared GGO:Bi3t, Eu3t phosphors exhibited color-tunable emissions from blue (Bi3t) to red (Eu3t) with increasing the Eu3t doping concentration via a high-efficiency energy transfer process. Moreover, the mechanism of energy transfer from Bi3t to Eu3t ions was determined to be the dipole-quadrupole interaction. Impressively, the optimal GGO:0.05Bi3t, 0.12Eu3t phosphors had an outstanding IQE as great as 88% and good thermal stability. All these meaningful results demonstrated that blue-red color-tunable GGO:Bi3t, Eu3t phosphors have potential applications in white light-emitting diodes (LEDs) and plant growth LEDs.
关键词： Gd2GeO5,Energy transfer,Phosphors,Eu3t,Bi3t,Color-tunable emissions
更新于2025-09-23 15:19:57
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Optical temperature sensing of Eu3+-doped oxyhalide glasses containing CsPbBr3 perovskite quantum dots
摘要： A new strategy for optical thermometer with high sensitivity was developed herein by employing exciton recombination of CsPbBr3 quantum dots as temperature detecting signal and 4f→4f transition Eu3t ions as reference one. A series of structural and spectroscopic characterizations confirmed that CsPbBr3 perovskite quantum dots were successfully precipitated and Eu3t doping activators remained in glass matrix. Benefited from their completely different thermal-quenching behaviors, fluorescence intensity ratio of exciton recombination and Eu3t emission in nanocomposite exhibited excellent temperature sensing property in the temperature ranging from 93 K to 383 K. The maximum absolute and relative temperature sensitivity can reach as high as 0.0224 K-1 and 2.25% K-1, respectively. We believe that this work will exploit an effective pathway for developing innovative non-contact optical thermometric materials.
关键词： Glass,Perovskite quantum dots,Eu3t,Temperature sensing,CsPbBr3
更新于2025-09-11 14:15:04
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Eu3+-doped fluoro-telluroborate glasses as red-emitting components for W-LEDs application
摘要： From 0.1 up to 2.5 mol% Eu3t-doped fluro-telluroborate glasses as red light-emitting components for white-light-emitting diodes (WLEDs) were investigated. Non-periodicity in the atomic arrangements was studied through the XRD pattern. The photoluminescence (PL) spectra were recorded under blue light (464 nm) excitation and analyzed. All the PL spectra exhibit an intense peak at 612 nm for 5D0 → 7F2 transition, revealing their red photoemission. Optimal PL emissions were achieved for 1.0 mol% Eu3t-doped sample. The CIE chromaticity coordinates for all the glasses (x ? ~0.69, y ? ~0.30) fall within the red color region. The J?O parameters (Ω2, Ω4) were calculated following the emission spectra of Eu3t-doped samples and the intensity parameters (Ω2>Ω4), as well as the high asymmetry ratio (R/O), indicate the low ionicity in all the studied glasses. Using the J-O parameters, several radiative features like total emission transition probability (AT), branching ratios (radiative (βR) & experimental (βexp)), stimulated emission cross-section (σEP), gain bandwidth (σEP × λeff), and optical gain (σEP × τrad) were evaluated. All the luminescence decay curves fit well to non-exponential function and decay times were decreased at Eu3t concentration >0.5 mol%. The evaluated σEP = 19.684 × 10?21 cm2, βexp = 0.759, τexp = 1.325 ms, minimum non-radiative relaxation, WNR = 296/s, and 60.78% of quantum efficiency (η) for 1.0 mol% Eu3t-doped glass for 5D0 → 7F2 transition indicates its promising features for red light-emitting optical devices and also as a red component in WLEDs.
关键词： Luminescence features,Decay lifetimes,Eu3t,White LEDs,Radiative properties,CIE chromaticity coordinates
更新于2025-09-11 14:15:04