基于硫系玻璃的大视场红外光学系统无热化设计

在大视场红外光学系统中,基于普通红外光学材料实现的光学被动无热化系统存在透镜数量多且不易实现轻量化、小型化的技术问题.为解决这个问题,采用硫系玻璃与常用红外材料组合来实现光学被动无热化,并设计了一种视场为40°×32.5°、工作波段为8～12μm、F数为1.0、工作温度范围为-55℃～+70℃的小型化非制冷红外成像光学...     

Nonlinear Optical Sulfides LiMGa8S14 (M = Rb/Ba,Cs/Ba) Created by Li+ Driven 2D Centrosymmetric to 3D Noncentrosymmetric Transformation

Cations that can regulate the configuration of anion group are greatly important but regularly unheeded. Herein, the structural transformation from 2D CS to 3D noncentrosymmetric (NCS, which is the prerequisite for second-order NLO effect) is rationally designed to newly afford two sulfides LiMGa₈S₁₄ (M = Rb/Ba, 1 ; Cs/Ba, 2 ) by introducing the smallest alkali metal Li⁺ cation into the interlamination of 2D centrosymmetric (CS) RbGaS₂. The unusual frameworks of 1 and 2 are constructed from C₂-type [Ga₄S₁₁] supertetrahedrons in a highly parallel arrangement. 1 and 2 display distinguished NLO performances, including strong phase-matchable second-harmonic generation (SHG) intensities (0.8 and 0.9 × AgGaS₂ at 1910 nm), wide optical band gaps (3.24 and 3.32 eV), and low coefficient of thermal expansion for favorable laser-induced damage thresholds (LIDTs, 4.7, and 7.6 × AgGaS₂ at 1064 nm), which fulfill the criteria of superior NLO candidates (SHG intensity >0.5 × AGS and band gap >3.0 eV). Remarkably, 1 and 2 melt congruently at 873.8 and 870.5 °C, respectively, which endows them with the potential of growing bulk crystals by the Bridgeman-Stockbarge method. This investigated system provides a new avenue for the structural evolution from layered CS to 3D NCS of NLO materials.     

Preparation and refractive index characterization of chalcogenide glasses with gradient refractive index

Infrared gradient refractive index (GRIN) lenses have great application value and potential in multispectral imaging systems. This study reports various chalcogenide axial GRIN glasses prepared using the hot-pressing diffusion method. It is worth noting that the S4–S60 GRIN sample has a difference in refractive index (RI) Δn of greater than 0.3 and a diffusion depth of about 5 mm, which is the deepest diffusion depth reported in chalcogenide glass to date. In addition, the linear portion in the profile of the GRIN sample has a RI difference of 0.15 and a thickness of 1.2 mm. The effects of the temperature, concentration difference, and diffusion time on the sample diffusion process are discussed. The dispersion properties of the GRIN samples were further calculated, providing a new option for correcting chromatic aberrations in optical systems. In addition, a method for the indirect nondestructive characterization of sample RI using the Raman intensity ratio is proposed, and the reliability of the method is verified by practical experiments, which is convenient for the subsequent measurement of the GRIN profile.     

Effect of residual chlorine on fluorescence emission of Dy3+ doped chalcogenide glasses with low gallium content

Chlorine or chlorides are usually used as a dehydrating agent for removing the O-H or S(Se)-H in the preparation of high-purity chalcogenide glasses. However, the residual chlorine in some rare-earth ions doped chalcogenide glasses was found to have a great negative impact on fluorescence emission. In this work, the effect of residual chlorine on the fluorescence emission of Dy³⁺ ions in serial (Ge)GaAsSbS glasses was studied quantitatively, and the reasons were discussed. Cl₂ gas and SbCl₃ were used as the source of chlorine and their residual contents were controlled by the post-distillation process and added content, respectively. The results can give some suggestions for how to eliminate the negative effects of chlorine and improve the glass’ optical gain properties.     

Direct comparison of surface crystal growth kinetics in chalcogenide glass measured by microscopy and DSC

Surface crystallization in fine powder Se₇₀Te₃₀ chalcogenide glass was studied by differential scanning calorimetry (DSC) and optical microscopy. A complex kinetic analysis of these experimental data reveals that the contracting sphere mechanism (R3 model) is the rate determining step of crystal growth, and the conventional Johnson–Mehl–Avrami–Kolmogorov model cannot be used in this case. Moreover, it is clearly shown that the particle size distribution should be considered in crystallization studies. Actually, when the particle size effect is taken into account, the simulated DSC curves for the R3 model agree very well with the experimental data over the entire temperature range. The crystallization kinetics determined from the nonisothermal DSC data are consistent with previously reported isothermal crystallization data for the same powder fraction. The crystal growth rate calculated from isothermal and nonisothermal DSC data agrees very well with the microscopically measured surface and bulk crystal growth rate.     

One-pot hydrothermal synthesis of Cu2Te/NiTe nanocomposite materials: A structural,morphological, and optical study

Due to various structural and optical properties, metal chalcogenide nanomaterials are favorable candidates for different optoelectronic applications. In the current report, Cu₂Te/NiTe nanocomposites were synthesized via the facile hydrothermal method. With the variation of concentration of Cu and Ni, various materials had been prepared along with pure Cu₂Te and NiTe. The observed several vibrational modes in the material through the Raman spectroscopy are well agreed with the appearing phases. The morphological study confirmed the nanostructures are combination of nanoparticles with sheets. The size of nanoparticles varied in the range of 66–34 nm. The absorbance spectra of the nanocomposite exhibit a blueshift and support the enhancement in the optical bandgap. The value of bandgap energy of the composite samples has been noted in the range of 1.8–2.2 eV. This bandgap range enables the material for various optoelectronic applications such as solar cell and other photovoltaic devices. Thermal analysis of the material demonstrates the presences of several endothermic and exothermic peaks. Thus, several studies on the material prevail its various applicability as optoelectronics as well as other thermal application.     

Expanding the Perovskite Periodic Table to Include Chalcogenide Alloys with Tunable Band Gap Spanning 1.5–1.9 eV

Optoelectronic technologies are based on families of semiconductor alloys. It is rare that a new semiconductor alloy family is developed to the point where epitaxial growth is possible; since the 1950s, this has happened approximately once per decade. Herein, this work demonstrates epitaxial thin film growth of semiconducting chalcogenide perovskite alloys in the Ba-Zr-S-Se system by gas-source molecular beam epitaxy (MBE).  This work stabilizes the full range y = 0 − 3 of compositions BaZrS_(3-y)Se_y in the perovskite structure. The resulting films are environmentally stable and the direct band gap (E_g) varies strongly with Se content, as predicted by theory, with E_g = 1.9 − 1.5 eV for y = 0 − 3. This creates possibilities for visible and near-infrared (VIS–NIR) optoelectronics, solid-state lighting, and solar cells using chalcogenide perovskites.     

Prospect for Bismuth/Antimony Chalcohalides-Based Solar Cells

Inorganic–organic hybrid lead halide perovskites are emerging optoelectronic materials for solar cell application. However, the toxicity concerns and poor stability largely hamper their practical applications. For these reasons, the search for “perovskite-inspired” alternatives, having the same advantages but overcoming the drawbacks of the lead-based one, has become an important sector in the field. Among the candidates, Bi³⁺ and Sb³⁺ containing materials are of great interest, due to their electronic structures resembling the Pb²⁺. Bismuth/antimony chalcohalides have been known for a long time as the potential absorber in photovoltaics, even if their performances are still low. Interestingly, pnictogen chalcohalides can be the stepping stone toward numerous quaternary compounds, including some perovskite structures. The understanding of the fundamental properties and the current limitations of both the starting ternary compounds and the final quaternary materials can allow the achievement of improved photovoltaic absorbers, stable, and efficient. In this review, the fundamental properties and device performances of many ternary pnictogen chalcohalides and the derived quaternary compounds are summarized, focusing on the different preparation strategies.