Novel Ge–Ga–Te–CsBr Glass System with Ultrahigh Resolvability of Halide

International audienceCO2 molecule, one of the main molecules to create new life, should be probed accurately to detect the existence of life in exoplanets. The primary signature of CO2 molecule is approximately 15 μm, and traditional S- and Se-based glass fibers are unsuitable. Thus, Te-based glass is the only ideal candidate glass for far-infrared detection. In this study, a new kind of Te-based chalcohalide glass system was discovered with relatively stable and large optical band gap. A traditional melt-quenching method was adopted to prepare a series of (Ge15Ga10Te75)100-x (CsBr)x chalcogenide glass samples. Experiment results indicate that the glass-forming ability and thermal properties of glass samples were improved when CsBr was added in the host of Ge–Ga–Te glass. Ge–Ga–Te glass could remarkably dissolve CsBr content as much as 85 at.%, which is the highest halide content in all reports for Te-based chalcohalide glasses. Moreover, ΔT values of these glass samples were all above 100 °C. The glass sample (Ge15Ga10Te75)65 (CsBr)35 with ΔT of 119 °C was the largest, which was 7 °C larger than that of Ge15Ga10Te75 host glass. The infrared transmission spectra of these glasses show that the far-infrared cut-off wavelengths of (Ge15Ga10Te75)100-x (CsBr)x chalcogenide glasses were all beyond 25 μm. In conclusion, (Ge15Ga10Te75)100-x (CsBr)x chalcogenide glasses are potential materials for far-infrared optical applicatio

Novel NaI improved Ge–Ga–Te far-infrared chalcogenide glasses

International audienceIn this study, a novel Te-based glass system was investigated. Some properties of Ge–Ga–Te–NaI chalcogenide glasses such as physical, thermal and optical transmitting were discussed. XRD patterns show this glass system with best amorphous state can dissolve content of NaI as much as 35 at.%. The lowest cut-off wavelength of glass samples is 1645 nm which is the smallest wavelength among the reported Te-based glasses doping with halide. DSC curves indicate that all glass samples have good thermal stabilities (ΔT > 100 °C) and the highest ΔT value corresponding to (Ge15Ga10Te75)85(NaI)15 glass is 120 °C which is 8 °C greater than that of Ge–Ga–Te host glass. The infrared spectra manifest Ge–Ga–Te–NaI chalcogenide glass system has a wide infrared transmission window between 1.6 μm and 20 μm. Consequently, Ge–Ga–Te–NaI glasses can be a candidate material for far infrared optic imaging and bio-sensing application

Fabrication And Characterization Of Multimaterial Chalcogenide Glass Fiber Tapers With High Numerical Apertures

This paper reports on the fabrication and characterization of multimaterial chalcogenide fiber tapers that have high numerical apertures (NAs). We first fabricated multimaterial As2Se3-As2S3 chalcogenide fiber preforms via a modified one-step coextrusion process. The preforms were drawn into multi- and single-mode fibers with high NAs (∼1.45), whose core/cladding diameters were 103/207 and 11/246 μm, respectively. The outer diameter of the fiber was tapered from a few hundred microns to approximately two microns through a self-developed automatic tapering process. Simulation results showed that the zero-dispersion wavelengths (ZDWs) of the tapers were shorter than 2 μm, indicating that the tapers can be conveniently pumped by commercial short wavelength infrared lasers. We also experimentally demonstrated the supercontinuum generation (SCG) in a 15-cm-long multimaterial As2Se3-As2S3 chalcogenide taper with 1.9 μm core diameter and the ZDW was shifted to 3.3 μm. When pumping the taper with 100 fs short pulses at 3.4 μm, a 20 dB spectral of the generated supercontinuum spans from 1.5 μm to longer than 4.8 μm

Analysis of SF6 contact based on QPSO-SVR

In the condition evaluation of the high-voltage SF6 circuit breaker, contact resistance and mass loss have a significant impact on the arc contact. To that end, this paper proposes a method based on quantum particle swarm optimization and support vector regression (QPSO-SVR), the implementation of which can effectively predict the contact resistance increment and mass loss of the circuit breaker arc contacts under different arc current conditions, and the best support vector regression (SVR) algorithm training parameters are obtained through experimental data. To validate the proposed method’s accuracy, it is compared to other prediction methods, and the results show that the QPSO-SVR method has good predictive ability for experimental data under different discharge parameters. The relative error of prediction for contact resistance increment is 3.023%, and the relative error of prediction for mass loss is 4.61%, indicating good accuracy and robustness. It can serve as a reference for the maintenance of high-voltage SF6 circuit breakers, which is useful. It is of great significance to the maintenance of SF6 circuit breaker

Stable CsPb1- xZn xI3Colloidal Quantum Dots with Ultralow Density of Trap States for High-Performance Solar Cells

All inorganic halide perovskites in the form of colloidal quantum dots (QDs) have come into people's view as one of the potential materials for the high-efficiency solar cells; nevertheless, the high surface trap density and poor stability of QDs restrict the performance improvement and application. Here, we obtain colloidal inorganic perovskite CsPb1-xZnxI3 QDs by the hot-injection synthesis process with the addition of ZnCl2. Synchrotron-based X-ray absorption fine structures demonstrate that the guest Zn2+ ions are doped into the CsPbI3 structure to improve the local ordering of the lattice of the perovskite, reducing the octahedral distortions. The increase of the Goldschmidt tolerance factor and the Pb-I bond energy also enhance the stability of the perovskite structure. Furthermore, the Cl- ions from ZnCl2 occupy the iodide vacancies of the perovskite to decrease the nonradiative recombination. The synergistic effect of doping and defect passivation makes for stable colloidal CsPb0.97Zn0.03I3 QDs with ultralow density of trap states. The champion solar cell based on the QDs shows a power conversion efficiency of 14.8% and a largely improved stability under ambient conditions

Far-infrared Optical Glasses and Fibers Based on Ge-Te-Se Glass System

International audienceGexTe65Se(35-x) (x = 20, 22, 23, 24, in mole fraction, x%) Te-based chalcogenide glasses were prepared by a conventional melt-quenching method in a silica tube under vacuum. The performance of these glasses was analyzed by X-ray diffraction, differential scanning calorimetry (DSC), visible/near-infrared (IR) absorption spectroscopy and infrared transmission spectroscopy. These glasses appeared to have excellent thermal stability and transmission properties. There was no crystallization peak on the DSC curve for the two glass compositions, namely, Ge23Te65Se12 and Ge24Te65Se11, indicating a notably enhanced resistance to crystallization and a maximum value of Tg at 188 for the glass composition Ge24Te65Se11. The optical transmission window was from 1.8 μm in the bandgap region to 18 μm in the phonon region. A distillation process that could effectively eliminate the absorption bands in the IR region was used for these glasses. The fabrication (rod-in-tube method) and fiber drawing were both conducted with glass compositions of Ge23Te65Se12 and Ge24Te65Se11 as cladding and core, respectively. The Ge-Te-Se infrared optical fiber with core-cladding structure exhibited good fiber drawing properties

Enhanced third-order optical nonlinearity and photon luminescence of Sn(2+)in gold nanoparticles embedded chalcogenide glasses

International audienceIn this work, we successfully prepared gold nanoparticles (AuNPs) within a germanium-tin-sulfur (Ge-Sn-S, GSS) chalcogenide glass (ChG). The formation of AuNPs in the GSS ChG relies on the reduction capacity of Sn(2+)ions, which we found their existence in the glass matrix by the characteristic emissions at nearly 450 nm. The AuNPs exhibit strong optical activity which caused a significant enhancement of third-order optical nonlinearity of the GSS ChG as well as photon luminescence of the Sn(2+)ions. In addition, optical properties the AuNPs-embedded GSS ChGs can be modified by further gold doping and one-step heat-treatment process

Fabrication and characterization of bare Ge-Sb-Se chalcogenide glass fiber taper

In this work, Ge15Sb20Se65 bare glass fiber with a diameter of 500 μm was fabricated, and then tapered with different tapering parameters. The analysis of Raman and energy dispersive X-ray spectra (EDS) indicated that, a slight change in the chemical composition of the glass, fiber and tapering fiber has negligible effect on the glass structure. It was found that, the waist diameter decreases exponentially with increasing tapering length and speed, and high quality taper fiber with the cone diameter of 2.65 μm can be achieved under the optimal tapering conditions. Finally, the simulated and experimental results of the output transmission under different waist length and taper ratio show that the transmission decreases with increasing waist length and taper ratioThe Project Sponsored by the National Natural Science Foundation of China (Nos. 61435009 and 61377099), and K. C. Wong Magna Fund in Ningbo University

Controllability of Graphene Oxide Doxorubicin Loading Capacity Based on Density Functional Theory

Graphene can be used as a drug carrier of doxorubicin (DOX) to reduce the side effects of doxorubicin. However, there is limited research on the surface chemical modifications and biological effects of graphene oxide (GO). Therefore, it is necessary to explore the DOX affinity of different oxygen-containing functional groups in the graphene system. We constructed graphene system models and studied the structure and distribution of epoxy and hydroxyl groups on the carbon surface. Based on molecular dynamics simulations and density functional theory (DFT), we investigated the interaction between DOX and either pristine graphene or GO with different ratios of oxygen-containing groups. The hydroxyl groups exhibited a stronger affinity for DOX than the epoxy groups. Therefore, the DOX loading capacity of graphene systems can be adjusted by increasing the ratio of hydroxyl to epoxy groups on the carbon surface