Effective ionic transport in AgI-based Ge(Ga)–Sb–S chalcogenide glasses

AgI-based Ge–Sb–S, Ga–Sb–S, and Ge–Ga–Sb–S chalcogenide glasses were designed and prepared by melt-quenching, thereafter their thermal properties and conductive performance were comparatively investigated on the basis of their composition-induced network structures. Glass transition in each sample was examined by DSC measurements. Results showed that the samples containing Ge had a higher thermal stability than the Ga–Sb–S–AgI sample, and the Ge–Sb–S–AgI sample obtained had the highest conductivity ion. Raman spectrum analysis was performed, and the results indicated that the [GeS_4-xI_x] structural units and [SbS_3−xI_x] pyramids in the matrix produced effective ion transport channel for dissolved conductive Ag⁺ ions. In the matrix containing Ga, the [Ga(Ge)S_4-xI_x] structure was consumed by part of [S₃Ga–GaS₃] ethane-like units, which had no contribution to the ion transition framework. The study provided the directions for composition and structure configuration control in effective conductive chalcogenide glasses.     

Investigation of the acousto-optical properties of Ge–As–Te–(Se) chalcogenide glasses at 10.6 μm wavelength

The acousto-optic parameters of Ge₁₀As_90−xTe_x (x = 30, 40, 50, 60, 70 mol%) and Ge₁₀As₂₀Te_70−ySe_y (y = 20, 30, 40, 50 mol%) glasses, were studied systematically to compare the pros and cons of Te-based and Se-based chalcogenide glasses in acousto-optic performance, as well as the thermomechanical properties. In the Ge₁₀As_90−xTe_x system, the acousto-optic figure of merit (M₂) increased with increased Te content, and the maximum M₂ of 2279 × 10⁻¹⁸ s³/g, which is 13 times that of commercial single-crystal Ge, obtained in Ge₁₀As₂₀Te₇₀ at 10.6 μm. However, its thermal properties and elastic modulus decreased and the acoustic attenuation (α) at different ultrasonic frequencies increased accordingly. In the Ge₁₀As₂₀Te_70−ySe_y system, the thermomechanical performance of the glasses improved with the introduction of Se element, the overall α was lower than that of Te-based chalcogenide glasses, and the minimum α was 5.29 dB/cm at 30 MHz ultrasonic frequency, although its M₂ was inferior to that of Te-based chalcogenide glasses. Additionally, the difference in the α of these glasses was smaller at low ultrasonic frequencies than at high ultrasonic frequencies. This work will promote the practical application of chalcogenide glasses as promising materials with outstanding acousto-optic properties in low ultrasonic frequency acousto-optic devices.     

Surface damage and threshold determination of Ge–As–Se glasses in femtosecond pulsed laser micromachining

Ge–As–Se chalcogenide glasses were prepared and the surface damage characteristics under femtosecond laser irradiation were experimentally investigated. Femtosecond laser beams with different power intensities, focusing depths, pulse repetition rates, and pulse numbers were employed to determine the damage thresholds of the samples. The surface morphologies and feature sizes of the damage craters were studied with regard to laser energy density to evaluate the damage circumstances of the glasses. The generation of the surface damage was also recorded by using different numbers of pulses. Results showed that the damage area increased monotonically with the laser power at low energy density and tended to saturation when reaching a critical value. According to the linear circumstances of laser energy density on the damage crater area, the average damage thresholds of the Ge–As–Se glasses with different repetition rates and pulse numbers were obtained. Results showed that the damage threshold decreased with the increase in pulse repetition rate and number of pulse.     

Preparation and properties of Ge–Ga–La–S–AgI chalcogenide glass

Chalcogenide glasses of 65GeS₂–(25–x)Ga₂S₃–10AgI–xLa₂S₃ (x=0, 1, 3, and 5 mol%) were fabricated through the traditional melt-quenching method. The effects of addition of La₂S₃ on physical, thermal and optical properties of the glass system were investigated. The results showed that the fabricated glasses possess considerably high glass transition temperature, exhibit improved mechanical property and excellent infrared transmission. A redshift at the visible absorbing cut-off edge is observed with increasing of La₂S₃ content. The direct and indirect optical band gap values are also calculated. Raman spectra analysis indicated that the band at 265 cm⁻¹ decreased in amplitude and a new peak at 230 cm⁻¹ was detected manifesting the formation of La-S bond in the network. In addition, the mid-infrared emission at 3.74 µm of the glasses doped with Tm³⁺ ions was achieved. The results indicated that the glasses are promising materials for mid-infrared applications such as imaging, remote sensing and lasers.     

Antistructural Defects in Ge–Te,As–Te,and Ge–As–Te Vitreous Alloys

Glass Physics and Chemistry - Emission Mössbauer spectroscopy on 119mmSn(119mSn), 119Sb(119mSn), 119mTe(119mSn), 125mTe(125Te), 125Sb(125Te), 125Sn(125Te), and 129mTe(129I) isotopes is used as...     

Effect of gallium addition on physical and structural properties of Ge–S chalcogenide glasses

GeS_2.5 chalcogenide glass was selected for studying effects of Ga addition on physical and structural properties. Glassy and partially crystallized samples of (100−x)GeS_2.5−xGa (5 mol% ≤ x ≤ 40 mol%) were prepared, and their thermal and optical properties were characterized. With increasing Ga content (x), values of T_g and optical band gap of glasses initially increased and then decreased, showing a maximal value at x = 25 mol%, that is, with stoichiometric composition of 85.7GeS₂·14.3Ga₂S₃. These changes were discussed and correlated to evolution of network structure, which was investigated by Raman spectra recorded in glassy matrices of (100−x)GeS_2.5−xGa (5 mol% ≤ x ≤ 40 mol%). This work contributes to understanding of composition–structure–property relationship of chalcogenide glasses.     

Microhardness and optical property of chalcogenide glasses and glass-ceramics of the Sn–Sb–Se ternary system

The microhardness of chalcogenide glasses (ChGs) of the Sn–Sb–Se (SSS) ternary system was investigated, and the correlation of microhardness with the mean coordination number of the SSS ChGs was determined. To prepare infrared-transparent SSS glass-ceramics (GCs), two SSS ChGs (A, Sn_6.23Sb_14.11Se_79.66; B, Sn_9.8Sb_17.22Se_72.98; by molar composition) were selected and thermally treated at 433 and 448 K, respectively. The improved microhardness (with values that increased by 11.5% and 7.3% for SSS ChG A and B, respectively) of the resulting SSS GCs is attributed to the formation of Sb₂Se₃ nanocrystals.     

Design and magneto-optical characteristics of Ge–Sb–S–PbI2 chalcogenide glasses with a high Verdet constant

To develop high-performance magneto-optical chalcogenide glasses and clarify the mechanisms of the Verdet constant, a series of GeS₂–Sb₂S₃–PbI₂ chalcogenide glasses were designed and fabricated, and their Faraday effects were investigated at a wavelength of 980 nm. A new parameter, that is, average polarizability, was proposed, and the results show that the Verdet constant has a good linear relationship with average polarizability, meaning that the Verdet constant of a chalcogenide glass can be directly estimated by its chemical constituents. The Verdet constant is as large as 0.200 min G⁻¹ cm⁻¹ at 980 nm for 22.5GeS₂–67.5Sb₂S₃–10PbI₂ composition glass, which is the largest value reported thus far for sulfide glasses; this glass also possesses good thermal and optical properties and therefore might be an attractive candidate for mid-infrared magneto-optical device applications.     

1.8–13 μm supercontinuum generation by pumping at normal dispersion regime of As–Se–Te glass fiber

Mid-infrared (MIR) band supercontinuum (SC) light source has highly important application prospects in aerospace, biomedicine, MIR sensing, and pollutant monitoring. As–Se–Te glass has high nonlinear refractive index, wide MIR transmission range and weak crystallization ability. As₄₀Se₄₀Te₂₀ glass fiber is suitable for producing wide MIR–SC spectrum. In this study, purified As₄₀Se₄₀Te₂₀ glass was prepared and unclad and step-index fibers were drawn. An unclad As₄₀Se₄₀Te₂₀ glass fiber with minimum loss of 1.7 dB/m at 8.8 μm was obtained. By pumping the unclad fiber in the normal dispersion region at 5 μm, we recorded the broadest SC generation spectrum, which covered 1.8–13 μm with a 30 dB spectral flatness, from a fiber with 15 cm length. Besides, As₄₀Se₄₀Te₂₀/As₄₀Se₄₂Te₁₈ step-index fiber with minimum loss of 5.6 dB/m at 5 μm was drawn from isolation extruded preform. The step-index fiber was pumped in the normal dispersion region at 5 μm, and the SC spectrum, covering 2.1–11.2 μm with a 40 dB spectral flatness, was recorded from a fiber with 15 cm length. The SC spectrum, which was achieved by pumping the As₄₀Se₄₀Te₂₀ fiber, covered almost all the transparent range of material.     

Ultralow voltage imprinting in GeS2–Ga2S3–AgI glasses for visible to middle-infrared diffraction gratings

A diffractive optical element (DOE) covering visible to middle-infrared regions is imprinted in chalcohalide glass by microthermal poling under ultralow voltages (~125 V). The effect of the poling voltage on the surface profiling, optical diffraction, optical transmittance, and anode-side structural rearrangement is investigated. Deformation of the surface profiling and diffraction order increase with increasing poling voltage, showing a saturation voltage of 125 V and a decrease in the transmittance within 10%. In addition to the normal vertical migration of silver ions, an obvious and unexpected transverse migration of silver ions and mutual structural transformation occur between homopolar bonds Ge–Ge (Ga–Ga) and S–S and the heteropolar bond Ge–S (Ga–S), which are key to forming the surface profiling and subsurface structures. Formation of the DOE mainly depends on the periodic subsurface microstructure rather than surface profiling. Thus, simple and inexpensive processes can fabricate broadband wavelength-based DOEs for military, medical and biological applications.     

Determination of the Fluctuation Free Volume Fraction for Glasses in the As–S(Se) Systems

The fraction f _g of fluctuation free volume frozen at the glass transition temperature is determined from the temperature dependence of the viscosity in terms of the Vogel–Fulcher–Tammann equation and the formula T _g = f _gln(1/f _g). The fluctuation free volume fractions obtained using these two procedures for glasses in the As–S(Se) systems are in quite reasonable agreement. It is demonstrated that the difference in the ratios between the fraction of fluctuation free volume and the lattice Grüneisen parameter for chalcogenide and oxygen-containing glasses is associated with the specific structure of the network of chalcogenide glasses. It is found that the dependence of the fluctuation free volume fraction on the mean coordination number Z _m, which characterizes the degree of connectivity of the network in noncrystalline materials, exhibits nonmonotonic behavior.     

Mössbauer 57Fe and 129I Spectra,as Well as the Local Environment of Atoms,in Chalcogenide CuI–AgI–As2Se3 and CuI–PbI2–SbI3–As2Se3 Films Deposited from Glass Solutions in N-Butylamine

Glass Physics and Chemistry - The results of a Mössbauer study of amorphous CuI–AgI–As2Se3 and CuI–PbI2–SbI3–As2Se3 films are presented, applied from glass...     

Modification of crystallization behavior,mechanical strength and optical property of Ge–S binary chalcogenide glass ceramics by trace CsCl incorporation

In present work, we discovered that nano-crystallization behavior of Ge–S binary chalcogenide glass can be remarkably improved by incorporating trace amount of CsCl as nucleating agent. After implementing an annealing process, the resultant Ge-S-CsCl chalcogenide glass ceramics (GSC ChGCs) possess fine distribution of crystallites belonging to GeS₂ and GeS mixture phase which could enhance mechanical strength and narrow bandgap energy of the original glass. By utilizing femtosecond Z-scan method, nonlinear optical properties of the GSC ChGCs were investigated in a spectral range from 750 to 900 nm. The results showed that the nonlinear absorption attribute of the GSC ChGCs can be enhanced by the crystallinity increase which led to the maximum two-photon absorption coefficient of 19.57 cm/GW at excitation wavelength of 750 nm, increased by 78% as compared to the original glass. This indicates the current GSC ChGCs a promising candidate for the optical limiting devices.     

Effect of halogen on imprinting gradient refractive index microstructure in GeS2–Ga2S3–NaX (X=F,Cl, Br,I) glasses for broadband infrared diffraction gratings

Chalcohalide glasses with a gradient refractive index (GRIN) microstructure were imprinted by microthermal poling for realizing diffractive optical elements covering the visible to middle-infrared wavelength range. The effect of halogen ions on the saturation poling voltage (U), surface profile, diffraction pattern, optical transmittance, GRIN microstructure, and structural rearrangement of poled glass is investigated. An effective imprinting formation region for a GRIN microstructure based on the U and glass composition is observed under fixed poling time and temperature. The onset U (60 V–150 V) and activation energy of mobile cations (0.449 eV–0.533 eV) decreases with the atomic number of the halogen from F to I, but the saturation diffractive order (8th to 11th levels) and phase difference (~0.08λ to 0.18λ) increases accordingly. The onset U and activation energy decrease with the deformability of the glass network and radius of the halogen ions. The phase difference and saturation diffractive orders decrease with the proportion and electronegativity of interval halogen atoms in the glass network. Thus, chalcohalide glasses with GRIN microstructures can be tailored by adjusting the type of halogen ions for realizing various diffraction optical elements.     

Effects of different glass formers on Li2S–P2S5–MS2 (M = Si,Ge, Sn) chalcogenide solid-state electrolytes

Chalcogenide solid-state electrolytes (SSEs) have been receiving growing attentions due to their high ionic conductivity and suitable mechanic properties, especially the Li₂S–P₂S₅ systems incorporated with a second glass network formers (Si, Ge, Sn, and so on) besides P. Although the ionic conductivities are generally enhanced with the second glass network formers, the comprehensive effects of different glass formers on other properties, including electrochemical, cycling, and air stability, remain elusive. To acquire deeper understanding, herein, three common but representative glass network formers (SiS₂, GeS₂, and SnS₂) were introduced into Li₂S–P₂S₅, and their individual effects were investigated systematically. The results of multiscale characterizations before and after lithium stripping/plating cycling confirmed that the introduction of metal cations (Ge, Sn) generally leads to worse electrochemical stability and shorter cycle life of these SSEs toward lithium metal compared with SSEs with nonmetal cation (Si) modification. However, the air stability is related to the binding energy of M–S (M = Si, Ge, Sn), which is consistent with the hard base soft acid theory. This work provides valuable understanding for designing pragmatic Li₂S–P₂S₅–MS₂-based SSEs with high electrochemistry, cycling, and air stability.     

Structural,luminescence and NMR studies on Nd3+-doped sodium–calcium-borate glasses for lasing applications

In this work, Neodymium (Nd³⁺) -doped borate glasses were synthesised by melt-quenching method and their structural as well as optical properties were analysed through XRD, Raman, NMR, DSC, UV–Visible, luminescence and decay studies for the possible application as laser gain medium. DSC and XRD results revealed that the glasses have high transition temperature and are in amorphous nature, respectively. The vibrational characteristics of the host matrices as well as the effect of Nd³⁺ incorporation were analysed by using Raman spectra, which exhibit majorly borate groups as supported by NMR results. The band gap energy of the glasses decreases with an increase in Nd³⁺ concentration. Using Judd-Oflet theory the characteristic intensity parameters (Ω_λ, λ = 2, 4 and 6) were calculated and further used for calculating the various radiative parameters from the emission spectra. The emission cross-section (σ_em) was estimated as high as 1.15 × 10⁻²⁰ cm² from the Füchtbauer–Landenburg (FL) equation for the dominant ⁴F_3/2→⁴I_11/2 (1056 nm) transition. The effect of Nd³⁺ concentration on the lifetime of the ⁴F_3/2 luminescent level was analysed from the decay curve analyses. From which, the corresponding quantum efficiency (η) was estimated and found as high as 54%. The investigated result suggests the prepared glasses can be utilized as gain medium to generate laser at around 1.05 μm.     

Mechanical,gamma rays and neutron radiation transmission properties for some ZnO–TeO2–P2O5-ZnX glasses

Oxyhalide glasses are utilized in the process of immobilizing nuclear waste and function as scintillating agents for the purpose of radiation detection. The objective of this study is to examine the enhanced mechanical and radiation attenuation characteristics of newly developed oxyhalide glasses by incorporating zinc-iodide. This study investigates the synthesis process, mechanical properties, and experimental gamma-neutron radiation transmission properties. A halogen-free base glass, consisting of an oxide mixture of P₂O₅, TeO₂, and ZnO, was synthesized. Following that, the initial glass composition was further strengthened by the addition of zinc bromide (ZnBr₂), zinc chloride (ZnCl₂), zinc fluoride (ZnF₂), and zinc iodide (ZnI₂) in a successive manner. The experimental configuration entailed positioning circular glass samples between a 133Ba radioisotope and a Canberra High Purity Germanium (HPGe) detector. The determination of attenuation coefficients is achieved through the measurement of individual attenuation properties. Afterwards, theoretical approaches are utilized to determine the mechanical characteristics of halogenated glasses, including Young's modulus (Y), Bulk modulus (K), Shear modulus (G), Longitudinal modulus (L), and Poisson's modulus (v). The results of the study suggest that the implementation of the halogenation process on the P₂O₅–TeO₂–ZnO base composition led to a significant enhancement in the examined properties. The incorporation of zinc-iodide in the halogenation process resulted in a significant improvement in the gamma absorption properties. The utilization of zinc in the halogenation process demonstrates multifunctional capabilities, which involve the potential to enhance various glass properties, including durability and gamma-ray absorption properties. It can be concluded that zinc-iodide demonstrates enhanced halogenation capabilities in comparison to zinc bromide, zinc chloride, and zinc fluoride.     

Study of Eu3+–Gd3+ co-doped Ba–Bi–B glasses for red-laser applications: Physical,structural, photoluminescence and time-resolved spectral characteristics

A series of Eu³⁺ and Eu³⁺/Gd³⁺ co-doped barium-bismuth-borate (Ba–Bi–B) glasses were prepared by melt-quench technique. And deliberated the physical, structural, and spectroscopic properties of all glasses and explored the energy transfer process from Gd³⁺ to Eu³⁺ ions. The density of glasses increased with increasing of Gd³⁺ concentration in co-doped glasses. Characteristics of steady-state and time-resolved photoluminescence (PL) of Eu-doped and Eu³⁺-Gd³⁺ co-doped glasses under different excitation wavelengths suggested the prospects of the investigated glass system for display device applications. PL spectrum displays a strong red emission peak centered at 612 nm due to the Eu³⁺: ⁵D₀→ ⁷F₂ transition. Less intense emissions centered at 577 nm (⁷F₀), 590 nm (⁷F₁), 651 nm (⁷F₃) and 700 nm (⁷F₄) are also observed from the radiative transitions of the excited state ⁵D₀ of Eu³⁺ions. The values of radiative parameters such as transition probability, branching ratios, and stimulated emission cross-sections were obtained from Judd–Ofelt theory analysis and indicated the aptness of the Ba–Bi–B glasses for optical devices. A 5-fold enhancement in the PL intensity was observed in 1.0 mol% Eu³⁺ and 3.0 mol% Gd³⁺ co-doped glass under λ_Exci. = 394 nm excitation. The calculated commission Internationale de l'eclairage color coordinates and correlated color temperature values show that the Ba–Bi–B glasses are useful for red-laser and display device applications.     

Preparation,Characterization, and Properties of Novel Polyimide–SiO2 Hybrid Composites Based on Bipyridine for Low Dielectric Applications

Novel low dielectric polyimide–SiO₂ hybrid materials containing bipyridine were prepared with three-step sol–gel process from poly(amic acid)s. (3-Aminopropyl)triethoxysilane as coupling agent was used to increase the intrachain chemical bonding between the polyimide and SiO₂ groups. The thermal, dielectric, and physical properties of the hybrid materials were investigated and correlated with the porous structure. The glass transition temperatures of all the hybrids were found to be higher than polyimides. The effect of SiO₂ groups on the porous structure and dielectric properties was investigated. The dielectric constant of the hybrid materials was observed a decrease from 3.30 to 2.15 with increased SiO₂ amount.     

Structural–chemical features and mechanism of crystallization of TlAsX<Subscript>2</Subscript> glasses (X = S,Se)

The vibrational IR spectra of polymer-chain glasses and single crystals of TlAsX₂ (X = S, Se) have been studied. The results of the kinetic study of the surface isothermal crystallization of glasses are theoretically anlayzed in different ways, taking into account the peculiarities of their structure. The semiempirical calculation of the temperature dependence of nonreconstructive crystal growth rate is performed. It is shown that the layered stationary growth of crystals in the TlAsS₂ glass occurs on screw dislocations. In the TlAsSe₂ glass the transition from a dislocation mechanism to two-dimensional nucleation and the layered growth of crystals is possible at supercooling of more than 120°C.