Papers by Keyword: Chalcogenide Glass

Abstract: We have prepared Ge_xGa₄S_96-x glasses for x=22.5, 27, 30 and 33.3 and Ge_xGa₈S_92-x for x=32, 36 and measured their linear and nonlinear optical properties. The glasses exhibit broad transmission at a wavelength range from 1 to 12 μm. The evolution of linear, nonlinear index and two-photon absorption as a function of the content of Ge, and the relationship of n₂ and β with linear refractive index and optical bandgap are analyzed. While the evolution of n₂ and β is closer to the prediction by Sheik-Bahae et.al for optical nonlinearity of semiconductors. E_g of Ge-Ga-S is found to vary from 2.33 to 2.99eV, and the largest nonlinear index is 1.16×10^-14cm²/W at composition of Ge₃₂Ga₈S₆₀ .

Abstract: This paper describes a method for detecting defects inside high-refractive index gems. This method consists in immersion of a precious stone inside low-melting chalcogenide glass. After cooling, molten glass turns into a solid phase and is an optical cube. This cube can be photographed in layers and using OctoNus equimpment a 3D model of gemstone defects can be built. The proposed method allows you to effectively and accurately determine the coordinates of the defects in diamond and to offer the most profitable option for polishing a precious stone.

Abstract: This paper presents data on the mixed alkali effect in two fundamentally different systems: chalcogenide and oxide (phosphate). In the first system (Ag – Cu)_0.44AsSe_1.5, the predominantly ionic conductivity of silver-containing glasses is replaced by purely electronic in copper-containing, in the second - 0.5(Li₂O-Na₂O) – 0.4P₂O₅ – 0.1Nb₂O₅ carriers of electric current are alkaline ions and the extreme dependences of the electrical parameters associated with their joint migration.

Abstract: The study of glass components influence on the physical and chemical properties of As–S–Se–I glasses has the potential to help design glasses with the required properties. A change of certain glass properties upon the introduction of selenium into AsSI glass was demonstrated. Non-stoichiometric compounds along the As₂S₃-AsI₃-Se diagram section were investigated by differential thermal analysis, ultrasonic measurements, dilatometric measurements. It has been shown that the introduction of selenium decreases the glass solubility in water. Change in the glass properties with the change in the short-range structure studied by Raman spectroscopy was shown. These glasses can be used for creation of immersion lenses and optical adhesives which change radiation characteristics of mid-IR LEDs.

Abstract: Glassy solid electrolytes are important integral components for all-solid-state devices for energy storage and conversion. The use of multiple network formers is an important part of their design strategy for specific applications. In many glass systems the interaction between the different network formers results in strongly non-linear variations in physical properties (network former mixing (NFM) effects), requiring a detailed understanding on a structural basis.The issues to be addressed involve both the structural organization and connectivities within the framework, the local environments and spatial distributions of the mobile ions, and the dynamical aspects of ion transport, to be discussed in relation to possible phase separation or nano-segregation effects. Besides Raman and X-ray photoelectron spectroscopies, solid state nuclear magnetic resonance (NMR) methods are particularly useful for providing detailed answers to such issues. The present review introduces the basic principles of modern solid state NMR methods and their applications to glass structure, with a particular focus on the characterization of network-former mixing effects in the most common lithium and sodium conducting oxide and chalcogenide glass systems. Based on the current state of the literature reviewed in the present work, some emerging general principles governing structure/property correlations are identified, to be tested by further experimenteation in the future.

Abstract: The paper explains the nature of mid-gap absorption, amplification effect of photoluminescence (at mid-gap absorption), the mechanism of the ESR signal in chalcogenide glasses, as well as correlations between these phenomena, based on the barrier-cluster-heating model. It also discusses the mechanism of photo-induced structural changes, which play an important role in the application area.

Abstract: Positron annihilation lifetime spectroscopy combined with Doppler broadening of annihilation radiation was applied to study free-volume entities in GeS₂-Ga₂S₃ glasses affected by Ga additions. It is shown that Ga-related void sub-system plays a decisive role in positron trapping process, while the overall density variation is defined mainly by Ge-related sub-system. These results serve as basis for new characterization route for inner free-volume structure of these glasses.

Abstract: (100-x)Ge₂₃Se₆₇Sb₁₀-xRbI glasses were prepared by the melting technique. The structures and properties were investigated by using SEM, XRD, DSC, FTIR and Vickers hardness tester. It is found that, with increasing x, the glass-forming ability and the infrared transmittance of (100-x)Ge₂₃Se₆₇Sb₁₀-xRbI samples decrease, the thermal stability and the fracture toughness increase, the Vickers hardness increases first and then decreases. When the content of RbI is 1%, the hardness reaches the maximum value 1985 MPa, at this point, the fracture toughness reaches 10.41 MPamm^1/2.

Abstract: The far infrared lenses are widely used in vehicle and night vision instrument. A new far infrared lens is proposed to enhance their performance of danger recognition at night. It focuses on the infrared light of wavelength from 8µm ~12µm. The lens is based on the uncooled infrared detector with 320x240 pixels. Its main structure is made of one refractive-diffractive aspheric lens and two spherical lenses. To improve the luminous flux, the f-number is set to be less than 1. The field of view (FOV) of 23 degrees is wide enough to help monitor the dangerous signal around the car or community. In addition, in order to reduce the cost and improve the machinability of aspheric diffractive lens, the hot-moldable chalcogenide glass is chosen to be the material of lenses. As a result, the MTF (modulation transfer function) values of lens exceed 0.5 for all field angles at Nyquist frequency. It shows that the lens enjoys high imaging quality.

Abstract: Crystalline selenium nanostructures were synthesized from the reaction of a GeSe3 glass with water at 85°C for 144 hours. The hydrolysis of the Ge-Se bonds releases Se fragments in the solution where they form a colloidal suspension of amorphous nanospheres. The later evolve toward a more stable hexagonal phase (trigonal) leading to the anisotropic growth of one-dimensional monocrystalline structures. Filaments, bars and tubes of monocrystalline trigonal selenium were obtained with diameters ranging from 10 nm to 1 µm and aspect ratio up to 180. This simple process in aqueous solution opens new perspectives for the synthesis of 1D nanoparticles of trigonal selenium at large scale.