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Effect of Er3+-doping on 65GeS2-25Ga2S3-10CsCl glass probed by annihilating positrons
摘要： Effect of Er3+-doping resulting in pronounced mid-IR fluorescence functionality was examined first in chalcohalide 65GeS2-25Ga2S3-10CsCl glass using positron annihilation lifetime (PAL) spectroscopy. The detected PAL spectra were reconstructed from unconstrained x2-term analysis employing two-state simple trapping model for one kind of positron trapping free-volume defects, the parameterization being performed at the example of 65GeS2-25Ga2S3-10CsCl glass doped with 0.6 at. % of Er3+. The observed decrease in positron trapping rate was proved to be primary void-evolution process in this Er-activated glass, like in many other chalcogenide glasses affected by rare earth doping. The nature of this effect was explained in terms of positron trapping reduction model as competitive contribution of changed occupancy sites in Ga-modified glassy matrix available for rare earth ions and annihilating positrons.
关键词： Chalcohalide glass,Positron trapping reduction,Rare earth doping,Photoluminescence
更新于2025-09-23 15:23:52
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Engineering Tunable Broadband Near-Infrared Emission in Transparent Rare-Earth Doped Nanocrystals-in-Glass Composites via a Bottom-Up Strategy
摘要： Applications of trivalent rare earth (RE3+)-doped light sources in solid-state laser technology, optical communications, biolabeling, and solar energy management have stimulated a growing demand for broadband emission with flexible tunability and high efficiency. Codoping is a conventional strategy for manipulating the photoluminescence of active RE3+ ions. However, energy transfer between sensitizers and activators usually induces nonradiative migration depletion that brings detrimental luminescent quenching. Here, a transparent framework is employed to assemble ordered RE3+-doped emitters to extend the emission spectral range by extracting photons from a variety of RE3+ ions with sequential energy gradient. To block migration-mediated depletion between different RE3+ ions, a nanoscopic heterogeneous architecture is constructed to spatially confine the RE3+ clusters via a 'nanocrystals-in-glass composite' (NGC) structure. This bottom-up strategy endows the obtained RE3+-doped NGC with high emission intensity (nearly one order of magnitude enhancement) and broadband near-infrared emission from 1300 to 1600 nm, which covers nearly the whole low-loss optical communication window. Most crucially, NGC is a versatile approach to design tunable broadband emission for the potential applications in high-performance photonic devices, which also provides new opportunities for engineering multifunctional materials by integration and manipulation of diverse functional building units in a nanoscopic region.
关键词： luminescence,rare earth doping,broadband emission,nanocrystals-in-glass composite,near-infrared emission
更新于2025-09-23 15:22:29
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Rare Earth Doping of Topological Insulators: A Brief Review of Thin Film and Heterostructure Systems
摘要： Magnetic topological insulators (MTIs) are a novel materials class in which a topologically nontrivial electronic band structure coexists with long-range ferromagnetic order. The ferromagnetic ground state can break time-reversal symmetry, opening a gap in the topological surface states whose size is dependent on the magnitude of the magnetic moment. Doping with rare earth ions is one way to introduce higher magnetic moments into a material, however, in Bi2Te3 bulk crystals, the solubility limit is only a few percent. Using molecular beam epitaxy for the growth of doped (Sb,Bi)2(Se,Te)3 TI thin films, high doping concentrations can be achieved while preserving their high crystalline quality. The growth, structural, electronic, and magnetic properties of Dy, Ho, and Gd doped TI thin films will be reviewed. Indeed, high magnetic moments can be introduced into the TIs, which are, however, not ferromagnetically ordered. By making use of interfacial effects, magnetic long-range order in Dy doped Bi2Te3, proximity-coupled to the MTI Cr:Sb2Te3, has been achieved. Clearly, engineered MTI heterostructures offer new possibilities that combine the advantageous properties of different layers, and thus provide an ideal materials platform enabling the observation new quantum effects at higher temperatures.
关键词： rare earth doping,MBE,topological insulators,heterostructure,bismuth telluride,antimony telluride
更新于2025-09-23 15:22:29