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Fabrication and characterization of Ge–Ga–Sb–S glass microsphere lasers operating at $\sim 1.9\,{\rm{\mu }}{\rm{m}}$
摘要： We report the fabrication and characterization of germanium gallium antimony sul?de (Ge–Ga–Sb–S or 2S2G, doped with Tm3+ ions) microsphere lasers operating at ～1.9-μm spectral band. Compared to the chalcogenide glasses that are used in previous microsphere lasers, this 2S2G glass has a lower transition temperature and a higher characteristic temperature. This implies that 2S2G microspheres can be fabricated at lower temperatures and the crystallization problem in the sphere-forming process can be alleviated. We show that hundreds of high-quality microspheres (quality factors higher than 105) of various diameters can be produced simultaneously via a droplet sphere-forming method. Microspheres are coupled with silica ?ber tapers for optical characterizations. We demonstrate that Whispering Gallery mode (WGM) patterns in the 1.7–2.0 μm band can be conveniently obtained and that once the pump power exceeds a threshold, single- and multi-mode microsphere lasers can be generated. For a typical microsphere whose diameter is 258.64 μm, we demonstrate its laser threshold is 0.383 mW, the laser wavelength is 1907.38 nm, and the thermal sensitivity of the microsphere laser is 29.56 pm/?C.
关键词： chalcogenides,whispering gallery modes,microspheres laser
更新于2025-11-25 10:30:42
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BaHgGeSe4 and SrHgGeSe4: Two New Hg-based Infrared Nonlinear Optical Materials
摘要： New practically usable IR nonlinear optical (NLO) crystals, especially those suitable for high-efficient pumping of the commercial 1 μm laser, are in urgent demand. However, only a few new IR NLO materials have been grown into bulk crystals and realized IR laser output during the past twenty years due to the extreme difficulty in achieving the coexistence of various strongly-correlated properties. In the manuscript, based on the bonding characteristics of the Hg element and an efficient screening strategy for high-performance new crystals, we identified two new Hg-based IR nonlinear (NLO) materials, BaHgGeSe4 and SrHgGeSe4. They crystallize in the polar space group Ama2 with the distorted HgSe4 and GeSe4 tetrahedra aligned parallelly. They exhibit exceptional balance among all the preferred properties for practical applications, especially for high-efficient pumping of the commercial 1 μm laser: Their large band gap (~2.5 eV) can avoid the two-photon absorption of 1 μm laser and increase the laser damage threshold; They are phase matchable with very strong NLO response (5×AgGaS2); They can cover both the 3-5 μm and 8-12 μm atmospheric windows. Moreover, they melt congruently, which indicate that bulk crystals can be obtained by the Bridgman method. Their overall properties outperform the traditional materials AgGaQ2 (Q = S, Se) in a large degree. Detailed structural analysis and calculations elucidate the crucial role of cations in regulating the packing of the anionic groups and that of the highly-polarizable HgSe4 in balancing optical properties.
关键词： phase matchability,second harmonic generation,BaHgGeSe4,IR nonlinear optical materials,SrHgGeSe4,congruent-melting,Hg-based chalcogenides
更新于2025-11-19 16:56:35
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Ambient surface stability of thin film nanocrystalline Cu <sub/>3</sub> SbSe <sub/>4</sub> and structure-property relationships
摘要： Nanocrystalline materials have a high surface area, and hence may be significantly more reactive than their bulk counterparts under ambient conditions. This may affect device function in unexpected ways. Here, high quality crystalline Cu3SbSe4 nanocrystals are synthesized through a hot injection route, and thin films are deposited through a ligand exchange procedure. The electronic conductivity of the films increases significantly upon exposure to air, up to 80 Ω-1cm-1. This increase in conductivity is correlated to a surface oxidation as observed by XPS. The observed changes in the film upon exposure to ambient conditions are suggested to be critical for understanding the properties of these materials as they are incorporated into devices.
关键词： surface oxidation,earth abundant,copper antimony chalcogenides,hot injection,Thermoelectrics,nanoparticles
更新于2025-11-14 15:19:41
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Electronic Structure for Europium Chalcogenides with Modified Becke–Johnson Potential Plus an On-Site Coulomb U (mBJ+U)
摘要： The full potential linearized-augmented-plane-wave (FP-LAPW) method is generalized to a case of an all-electron fully-relativistic spin-polarized self-consistent band calculation based on the relativistic spin-density functional theory and the modified Becke–Johnson potential (TB-mBJ) plus an on-site coulomb U employed for greater generation of the band gap. The results show that these materials are semiconducting materials. The indirect energy gap obtained in this calculation is 1.63 eV, 1.79 eV and 1.96 eV for EuS, EuSe and EuTe, respectively. It is clear from the plots that LSDA + U is a poor technique for the calculation of the band gaps of chalcogenides (EuX). The calculated results for EuX (S, Se and Te) by mBJ + U are in good agreement with the experimental values as compared to the other calculated results.
关键词： FP-LAPW,europium chalcogenides,mBJ + U,electronic structure.
更新于2025-09-23 15:22:29
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Fabrication of IR windows grade zinc selenide by the reactive diffusive process
摘要： The preparation of infra-red windows grade zinc selenide (ZnSe) by the reactive diffusion process between liquid zinc and selenium was the goal of present work. In this regards, high purity zinc and Se elements with a nominal composition of Zn50Se50 were capsulated in quartz ampoule and annealed in the temperature range of 550-950 °C. The wurtzite structure of zinc selenide phase was successfully obtained during annealing process beyond 750 oC. The hexagonal structure of zinc selenide was an unstable phase and totally transformed to the cubic construction by increasing the annealing temperature (950 °C) that is appropriate for infra-red windows application. The formation of zinc selenide phase during the annealing process has been performed by the development of an unceasing layer of porous zinc selenide compound in zinc/ selenium interface. The formation of porous zinc selenide can be associated to the different diffusion constants of selenium and zinc atoms in zinc selenide lattice based on the Kirkendall theory.
关键词： Interfaces,zinc selenide.,Kinetics,Chalcogenides
更新于2025-09-23 15:22:29
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Ab-Initio Prediction of Intrinsic Half-Metallicity in Binary Alkali–Metal Chalcogenides: KX (X=S, Se and Te)
摘要： First-principles full-potential linearized augmented plane-wave method based on density functional theory is used to investigate the structural, electronic and magnetic properties of KX (X ? S, Se and Te) binary alkali–metal chalcogenides compounds. These compounds in different crystalline phases, NaCl (B1), CsCl (B2), ZB (B3), NiAs (B81T, WZ (B4) and Pnma, were calculated within the generalized gradient approximation (GGA-PBE) and the modified Becke–Johnson approach (mBJ-GGA-PBE) for the exchange–correlation energy and potential. We found that the most stable phase for the KX binary compounds is the nonmagnetic Pnma phase. The calculated lattice parameters, bulk moduli, their first-pressure derivatives and internal parameters are in good agreement with the other theoretical data. The electronic band structure and density of states show that half-metallic and magnetic character arises, which can be attributed to the presence of spin-polarized p orbitals in the group VI elements. KX (X ? S, Se and Te) compounds, except for KSe and KTe in the CsCl and NiAs phases, show HM character in all phases, with an integer magnetic moment of 1 (cid:1)B per formula unit and HM gaps.
关键词： alkali metals,Density functional theory,half-metals,chalcogenides,ferromagnetism
更新于2025-09-23 15:22:29
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Photo-Induced Phase Transition of CdZnS Based Nanocomposite at Room Temperature Under Solar Irradiation
摘要： Photo-induced phase transition (PIPT) of CdZnS based nanocomposites that was performed at the room temperature under the solar light illumination is reported here for the first time. CdZnS particles were decorated on reduced graphene oxide (RGO) with a solvothermal process and consequently RGO-CdZnS-5%Pt nanocomposites (PC) have been synthesized as zinc blende (cubic) phase of CdZnS. Zinc blende structure (cubic) of CdZnS components of PC was turned to wurtzite (hexagonal) crystal structure with PIPT during the photocatalytic hydrogen evolution reaction. The band gap of the photocatalyst decreased from 2.42 to 2.19 eV and the hydrogen evolution rate increased from 37.3 to 184.0 μ mol h?1 due to the PIPT process.
关键词： Photo-induced phase transition,Hydrogen production,Metal chalcogenides,Photocatalyst
更新于2025-09-23 15:22:29
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PEGylated mesoporous Bi2S3 Nanostars loaded with Chlorin e6 and doxorubicin for fluorescence/CT imaging-guided multimodal therapy of Cancer
摘要： Taking advantage of the mesoporous structure of bismuth sulfide nanostars (Bi2S3 NSs), a chemotherapeutic drug of doxorubicin (DOX) and a photosensitizer of chlorin e6 (Ce6) were concurrently loaded in the PEGylated Bi2S3 NSs to formulate a multifunctional nanocomplex (BPDC NSs) for theranostics. BPDC NSs have excellent photothermal conversion efficiency and a capacity of yielding reactive oxygen species (ROS) upon laser irradiation, and can realize on-demand drug release by either pH-activation or thermal induction. Accumulation of the nanodrug could be monitored in real-time by infrared thermal imaging, fluorescence imaging and computed tomography (CT). More importantly, the combination effects of photothermal therapy (PTT), photodynamic therapy (PDT) and chemotherapy was demonstrated to dramatically suppress solid tumors without recurrence in vivo. Featured by the low systemic toxicity and high biocompatibility, this nanoplatform could be a promising derivative of Bi2S3 NSs for imaging-guided theranostics of cancer.
关键词： Controlled drug release,Cancer theranostics,Doxorubicin,Chlorin e6,Bismuth (Bi) chalcogenides
更新于2025-09-23 15:22:29
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Rational band design in metal chalcogenide Ba6Zn6HfS14: splitting orbitals, narrowing forbidden gap and boosting photocatalyst property
摘要： The insufficient light sources absorption often limits photocatalyst applications of metal chalcogenides because of their excessively broad band gap. Thus, it is necessary to discover and design a compound with rational band gap. Here, a new visible-light photocatalyst, Ba6Zn6HfS14, is prepared through the traditional high temperature solid-state reaction. A set of experiments on the visible-light decomposition of methylene blue demonstrated that the photocatalytic efficiency of Ba6Zn6HfS14 (0.00761 min-1) is improved, compared to that of Ba6Zn6ZrS14 (0.00553 min-1) which proved to be a previously reported visible-light photocatalyst with similar structure. The UV-visible reflection spectra demonstrated the energy gap of Ba6Zn6HfS14 (E1=1.45eV; E2 =2.55eV) is smaller than that of Ba6Zn6ZrS14 (E1 = 1.78eV; E2 = 2.50eV; E3 = 2.65eV). The Ba6Zn6HfS14 absorbs more visible light and exhibits preferably photocatalytic activity. The origin of splitted energy bands were elucidated via the first calculations.
关键词： band gap engineering,chalcogenides,visible-light photocatalyst
更新于2025-09-23 15:21:21
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The electronic and elasticity properties of new half-metallic chalcogenides Cu <sub/>3</sub> TMCh <sub/>4</sub> (TM?=?Cr, Fe and Ch?=?S, Se, Te): an <i>ab initio</i> study
摘要： The ternary copper-based chalcogenides Cu3TMCh4 (TM = Cr, Fe and Ch = S, Se, Te), which have simple cubic (SC) crystal structure and conform to P(cid:1)43m space group with 215 space number, have been investigated by spin-polarised generalised gradient approximation (GGA) in the framework of density functional theory (DFT). All systems have been considered in ferromagnetic (FM) order. The mechanical and thermal properties and the electronic band structures of these systems have been investigated after the well-optimised structural parameters have been obtained. The spin-polarised electronic band structures of all the systems exhibit half-metallic behaviour with band gaps in minority spin channel from 0.29 eV for Cu3FeTe4 to 1.08 eV for Cu3CrS4, while metallic band structures are observed for majority spins. This agrees with the calculated total magnetic moments which are close to integer values. The calculated negative formation enthalpies indicate the energetic and thermodynamic stability of these compounds. Moreover, the calculated elastic constants verify that these materials are stable mechanically due to satisfying Born stability criteria. The estimated anisotropy shear factors show that Cu3FeS4, Cu3FeSe4 and Cu3CrSe4 systems have nearly isotropic character with 1.004, 0.910, and 0.958 values, respectively, whereas other compounds have relatively low anisotropic behaviour.
关键词： electronic structure of bulk materials,density functional theory,chalcogenides,Half-metallic,mechanical properties of solids
更新于2025-09-23 15:21:21