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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Application of mosaicity induced disorder controlled rare earth nickelate thin films as THz transmission modulator
摘要： Here, we have studied mosaicity induced disorder (a unique type of disorder which is transferred from substrate template to film) controlled properties of rare earth nickelate thin films. While highly oriented film exhibits sharp metal to insulator transition (MIT) and Drude type of terahertz (THz) conductivity behavior, mosaic film exhibit much more subtle and broad transition and Drude-Smith type THz conductivity behavior. On the basis of such contrasting behavior, we propose application of these films as thermally controlled THz transmission modulator: oriented film as digital modulator while mosaic film as analog modulator.
关键词： metal to insulator transition,Drude-Smith model,rare earth nickelate,THz transmission modulator,mosaicity induced disorder
更新于2025-09-16 10:30:52
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Investigations on RE(TTA)3tppo (RE=Eu/Sm/Eu0.5 Sm0.5) rare earth β-diketonate complexes for OLEDs and solid state lighting
摘要： Rare earth hybrid organic β-diketonate complexes of Eu(III), TTA and tppo; Eu(TTA)3tppo, Sm(TTA)3tppo and Eu0.5Sm0.5(TTA)3tppo [Eu: europium, Sm: samarium, TTA: Thenoyl Trifluoro Acetone, tppo: Triphenylphosphine oxide] were synthesized by solution technique, maintaining pH 7. X-ray diffractogram of all the complexes revealed their crystalline nature. TGA curves infer their thermal stability to be in the range of 2300C - 2600C. The optical energy band gap of these complexes was found to be in the range of 3.08 to 3.20 eV. When RE(TTA)3tppo complexes were excited at 377 nm, 382 nm and 382 nm respectively, the emission spectra portrays red emission, peaking at 616 nm, 645 nm and 616 nm in solid state, while in solvated state, hypsochromic shift (shift toward lower wavelength) was noticed. CIE co-ordinates and color correlated temperature (CCT) of the complexes tuned according to their emission wavelength. These investigations provide a good deal of information regarding their suitability for the fabrication of red to blue tunable light emitting organic light emitting diodes (OLEDs), panel displays and solid state lighting panels on flexible substrates.
关键词： Samarium,flat panel displays,Rare earth β-diketonates,europium,OLED devices,solid state lighting
更新于2025-09-16 10:30:52
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High-performance upconversion luminescent waveguide using a rare-earth doped microtube with beveled ends
摘要： Upconversion luminescence-based waveguides can achieve optical signal transmission and visible light emission with near-infrared light excitation and their quality is highly dependent on the coupling efficiency between the light and waveguide. Here, a new luminescent waveguide formed by a rare-earth doped microtube with beveled ends was designed to increase the optical coupling efficiency for vertical waveguide-excitation. The beveled end enabled the near-infrared light to effectively couple into the waveguide and produce a visible transmission pattern and directional emission, which was not possible using conventional luminescent waveguides without beveled ends. It was found that the beveled end can not only improve the input and the output signal efficiency, but also control the coupling efficiency and transmission pattern. In particular, a coupling efficiency of B68% could be obtained with the optimized beveled waveguide with a rotation angle of 301. The high optical coupling efficiency and multi-channel luminescent waveguide enabled by the microtube with beveled ends allowed for a deeper understanding of vertical waveguide excitation, and it extends the potential applications of luminescent waveguides for bioimaging and optical communication.
关键词： rare-earth doped microtube,beveled ends,upconversion luminescence,waveguide,optical coupling efficiency
更新于2025-09-16 10:30:52
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Graphene quantum dot-rare earth upconversion nanocages with extremely high efficiency of upconversion luminescence, stability and drug loading towards controlled delivery and cancer theranostics
摘要： The study reported one concept for fabrication of functional graphene quantum dot-rare earth upconversion nanocage. The nanocage exhibits extremely high efficiency of upconversion luminescence, stability and drug loading toward controlled delivery and cancer theranostics.
关键词： Cancer theranostics,Rare earth-based upconversion nanoparticle,Graphene quantum dot,Drug delivery
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Light Shaping for Reconfigurable Microscale Temperature Control
摘要： Recycling rare-earth elements (REEs) from Nd-Fe-B magnet waste is an important step towards building a sustainable REE supply chain. In this study, two different processes were systematically investigated and compared. In the leaching stage, the effect of increasing H2SO4 or HCl concentrations were studied and it was determined that, although both can successfully promote REEs, B, Fe and Co leaching, HCl solutions extracted a wider range of metals. After leaching, the oxalate and double-sulfate precipitation methods were utilized to separate REEs from either HCl or H2SO4 leachates. Results suggest that, although > 99% REEs precipitation rates could be achieved with oxalate, the purity of REE-containing products is significantly affected by impurities like Fe and Co. In contrast, REE double-sulfate precipitation resulted in a product purity of > 99%; however, high levels of Na2SO4 (8 times the stoichiometric amount) were needed to achieve > 98% of REE precipitation.
关键词： rare-earth elements,precipitation,leaching,Nd-Fe-B magnets,recycling
更新于2025-09-12 10:27:22
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Controlling multiphoton excited energy transfer from Tm <sup>3+</sup> to Yb <sup>3+</sup> ions by a phase-shaped femtosecond laser field
摘要： The ability to control the energy transfer in rare-earth ion-doped luminescent materials is very important for various related application areas such as color display, bio-labeling, and new light sources. Here, a phase-shaped femtosecond laser field is first proposed to control the transfer of multiphoton excited energy from Tm3+ to Yb3+ ions in co-doped glass ceramics. Tm3+ ions are first sensitized by femtosecond laser-induced multiphoton absorption, and then a highly efficient energy transfer occurs between the highly excited state Tm3+ sensitizers and the ground-state Yb3+ activators. The laser peak intensity and polarization dependences of the laser-induced luminescence intensities are shown to serve as proof of the multiphoton excited energy transfer pathway. The efficiency of the multiphoton excited energy transfer can be efficiently enhanced or completely suppressed by optimizing the spectral phase of the femtosecond laser with a feedback control strategy based on a genetic algorithm. A (1 + 2) resonance-mediated three-photon excitation model is presented to explain the experimental observations. This study provides a new way to induce and control the energy transfer in rare-earth ion-doped luminescent materials, and should have a positive contribution to the development of related applications.
关键词： energy transfer,rare-earth ions,femtosecond laser,luminescent materials,multiphoton absorption
更新于2025-09-12 10:27:22
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A New Co-Substitution Strategy as a Model to Study a Rare-Earth-Free Spinel-Type Phosphor with Red Emissions and Its Application in Light-Emitting Diodes
摘要： The substitution of metal sites in Mg2TiO4 substrate leads to charge imbalance that will be closely related to a variety of changes including lattice structure, cell distortion, and photophysical properties. Herein, the co-substitution strategy of [Ga3+?Ga3+] for [Mg2+?Ti4+] and Sn4+ for Ti4+ achieves for the first time the novel Mg3Ga2SnO8 (MGS):xMn4+ (x = 0?3%) phosphors with efficient red emissions. In terms of X-ray powder diffraction (XRD) and Rietveld refinement analysis, MGS:Mn4+ possesses a structure isotypic of Mg2TiO4 in the cubic space group Fd3?m (227). There are two types of octahedra for Mn4+ ions in this structure, where Ga3+ ions completely occupy a group of octahedral sites and Mg2+/Sn4+ has been randomly distributed over another group of octahedral sites. A strong excitation band in the broad spectral range (220?550 nm) has been identified, thus facilitating the commercial uses for blue LED chips excitation. An intense red emission band at 680 nm has been observed due to the characteristic 2Eg?4A2g transition of Mn4+ ions. A concentration quenching effect occurs when the Mn4+ content exceeds 1.5%, and the quenching mechanism is demonstrated to be dipole?quadrupole interactions. Temperature-dependent luminescence measurements support its good thermal stability, and the corresponding activation energy Ea is determined to be 0.2552 eV. The possible luminous mechanism of the Mn4+ ion is explained by the Tanabe?Sugano energy level diagram. The crystal field strength and the Racah parameters together with the nephelauxetic ratio are also determined for Mn4+ in the MGS lattice. High color rendition warm white-light-emitting diodes (WLEDs) based on the optimal phosphor MGS:1.5%Mn4+,1.5%Li+ possess a color rendering index and color temperature of 85.6 and 3658 K, respectively. Its feasibility for application in solid-state white lighting has been verified.
关键词： Co-substitution strategy,Light-emitting diodes,Red emissions,Spinel-type phosphor,Rare-earth-free
更新于2025-09-12 10:27:22
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Rare Earth Doped Optical Fibers with Multi-section Core
摘要： The gain bandwidth of a single-mode fiber is limited by the atomic transitions of one rare earth gain element. Here we overcome this long-standing challenge by designing a new single-mode fiber with multi-section core, where each section is doped with different gain element. We theoretically propose and experimentally demonstrate that this configuration provides a gain bandwidth well beyond the capability of conventional design, whereas the inclusion of multiple sections does not compromise single-mode operation or the quality of the transverse modal profile. This new fiber will be beneficial in realizing all fiber laser systems with few-cycle pulse duration or octave tunability.
关键词： Rare Earth Doped Optical Fibers,Gain Bandwidth,Fiber Laser Systems,Single-mode Fiber,Multi-section Core
更新于2025-09-12 10:27:22
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Rare-earth element doping in glass frit for improved performance in silicon solar cells
摘要： Glass frit plays an important role in the silver paste for silicon solar cells. In this work, we prepare glass frit doped with different rare-earth elements (Y, La, Sm, Er) and study how the doping element affects the performance of the solar cells. Solar cells with La-doped and Sm-doped glass frits show average conversion efficiencies higher than 17.5%, while solar cells with Y-doped or Er-doped frit show lower efficiencies. By analyzing the Raman spectra of the rare-earth doped glass frits, we find that the average coordination number of Te–O (NTe(cid:1)O) in the glass can be tuned by the rare-earth dopant. La or Sm doping leads to a moderate value of NTe(cid:1)O, which is believed to achieve a glass formation ability that optimizes the structure of the Ag–Si interface of the cell for the best performance.
关键词： rare-earth elements,glass frit,Solar cells,Raman spectra
更新于2025-09-12 10:27:22
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Ideal Laser Cooling Efficiency Utilizing Anti-Stokes Luminescence in Yb-Doped Yttrium Aluminum Garnet Powder Crystals; Yb添加イットリウムアルミニウムガーネット結晶粉末におけるアンチストークス発光を利用した理想レーザー冷却効率;
摘要： Laser cooling in rare-earth doped material using anti-Stokes photoluminescence (PL) caused by phonon annihilation realizes novel cooling devices without generating heat and vibration. Yb-doped yttrium aluminum garnet powder crystals, (Y:Yb)AG with the Yb concentration from 2 to 13 mol%, were fabricated by a solid state reaction method. PL of (Y:Yb)AG excited at 659 nm shows the maximum intensity at the Yb concentration of 6 mol% because of concentration quenching of the PL. When we resonantly excite at 1030 nm corresponding to the energy distance between the E5 and E3 levels of the f-f transition of Yb3+, obvious anti-Stoke PL signal has been observed at 968 nm. This result indicates that phonons are absorbed, and, then, an up-converted photon with the energy between the E5 and E1 levels is emitted. The relative cooling efficiency, defined by a product of the ideal cooling efficiency and the integrated PL intensity, becomes maximum at the 1030-nm excitation. The ideal cooling efficiency was estimated to be 1.9% at the Yb concentration of 6 mol% and the 1030-nm excitation at room temperature.
关键词： Self-absorption,Solid state reaction,Phonon absorption,(Y:Yb)AG,Rare-earth,Laser cooling in solids
更新于2025-09-11 14:15:04