Chalcogenide glasses with embedded ZnS nanocrystals: Potential mid‐infrared laser host for divalent transition metal ions

Chalcogenide glasses (ChGs) containing II‐VI chalcogenide (ChG) nanocrystals such as ZnS/Se have recently been intensively studied as promising mid‐infrared nonlinear optics and laser materials, yet preparation of pure‐phase II‐VI nanocrystals embedded in ChGs via controlled crystallization is still very challenging. In this study, a new system of ChGs and glass ceramics (GCs), viz., (100?x)As₂S₃–xZnSe (x = 0 ~ 30 mol%), is synthesized, and its physical and optical properties including density, molar volume, microhardness, glass transition temperature, glass network structure, transmission, and refractive index are comprehensively characterized. Significantly, it is initially demonstrated that pure ZnS nanocrystals can be precipitated in GCs simply by a thermal treatment process. The composition and thermal treatment temperature dependencies of crystallization are studied using X‐ray diffraction spectroscopy, and the morphology of the nanocrystals by high‐resolution transmission electron microscope. The ChG GCs with embedded ZnS nanocrystals retaining good transparency can be a potential host laser material for divalent transition metals (e.g., Cr²⁺/Fe²⁺, etc.), and thus used for ultrabroadband tunable continuous or ultra‐short‐pulsed mid‐infrared fiber lasers.     

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.     

Infrared GRIN GeS2–Sb2S3–CsCl chalcogenide glass–ceramics

Chalcogenide glasses show a unique potential for creating gradient refractive index (GRIN) lenses, which would reduce the size and weight of infrared thermal imaging system and remain/improve its performance. Here, we propose a new method that forms a GRIN chalcogenide glass–ceramics (GCs) by creating low refractive index (n) CsCl nanocrystals within a high n GeS₂–Sb₂S₃ glass matrix. After specific gradient thermal treatment, the GRIN structure of Δn ∼ 0.04 was formed through the gradient precipitation of CsCl. This work would pave a new path to design the GRIN chalcogenide GCs through a selective crystallization of halide crystals with low n.     

Multilayered chalcogenide glass with gradient index for reduced SWaP IR optical system

Gradient index (GRIN) lens could promote the lightweight and miniaturization of optical imaging system, but the development of IR GRIN lens is still in its infancy. A new series of As–S–Se chalcogenide glasses (ChGs) possessing similar glass transition temperature, excellent thermal stability, and large refractive index variation was developed, and these properties enabled them to become a good glass material catalog for co-molding multilayered GRIN IR lens. By employing precision molding, layer-stacked GRIN ChG was co-molded with a maximum refractive index variation of 0.47 at 4 μm, which was correlated to the variation of Raman intensity and elemental content. A mid-IR optical imaging system was designed and fabricated using the GRIN ChGs, and IR images were obtained. This multilayered GRIN ChG could lead to 18% smaller and 35% lighter SWaP IR optical system.     

Performance modification of third-order optical nonlinearity of chalcogenide glasses by nanocrystallization

We demonstrate the modification of the third-order optical nonlinearity (TONL) of chalcogenide glasses (within the GeS₂–In₂S₃–CsCl ternary system) by nanocrystallization, i.e., by controlling the precipitation of nanocrystals (in pure In₂S₃ phase) within the amorphous background. Compared with the parent glass, the resultant chalcogenide glass ceramics (ChGCs) have unchanged infrared transmittance but modifiable optical bandgap energy with treatment duration. Both nonlinear refraction coefficient and nonlinear absorption coefficient of the ChGCs are increased due to the appearance of In₂S₃ nanocrystals. ChGCs subjected to heat treatment for 1.3–2 h are found to exhibit the optimum TONL performance.     

Signature of rigidity percolation effect in dielectric behavior of germanium containing multi-component chalcogenide glasses (ChGs)

To develop new chalcogenide glasses (ChGs) as dielectric materials having a high dielectric constant and low dielectric loss, some quaternary glasses have been prepared from a novel third-generation Se–Te–Sn-Ge (STSG) system. This study reveals the effect of Ge addition on the dielectric relaxation and thermally activated a.c. conduction in a ternary ChG of Se–Te–Sn (STS) system. The compositional variation of the various dielectric and electrical parameters in the present STSG chalcogens rich non-oxide glasses Se_78-yGe_yTe₂₀Sn₂ (0 ≤ y ≤ 6) has been investigated. The results show that Ge plays a potential role in improving the dielectric properties of the parent STS glass.The dielectric relaxation and thermally assisted a.c. conduction have been investigated by examining the frequency/temperature dependence of dielectric constant/loss. The absence of the dielectric relaxation for the higher concentration of Ge indicates that the relationship of microstructure and dielectric properties can be explained in terms of the stiffness transition followed by the self-organization of the corner sharing and the edge-sharing arrangements of GeSe₄ phase.     

Analysis of the Composition of CuI–As2Se3 and CuI–PbI2–As2Se3 Chalcogenide Films by X-ray Fluorescence Spectroscopy

The chalcogenide films As₂Se₃, CuI–As₂Se₃, and CuI–PbI₂–As₂Se₃ are prepared through chemical deposition from an organic solvent and investigated by X-ray fluorescence spectroscopy. The contents of the main components of the chalcogenide films are compared by analyzing the intensity ratios for the AsK , SeK , and CuK lines. It is found that the content of the main components (As, Se, and Cu) is virtually the same in binary chalcogenide, pseudobinary, and multicomponent chalcogenide systems, no matter what the technique used for preparing the materials (films deposited from solutions of chalcogenide glasses in n-butylamine and bulk glasses). This result is consistent with a model of dissolution of vitreous semiconductors in organic bases (amine) according to which the fundamental properties of bulk glasses remain unchanged upon formation of the films. The experimental data indicate an analogy between the properties of the multicomponent chalcogenide glasses CuI–As₂Se₃ and CuI–PbI₂–As₂Se₃ and the chalcogenide glass–based films.     

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.     

Nanocomposites based on chalcogenide glass semiconductor and metal phtalocyanine

A novel technique for the fabrication of chalcogenide nanocomposites based on chalcogenide glass (ChGs) and manganese phtalocyanine (MnPc) is presented. The structural and optical characterization of obtained composites in comparison to chalcogenide glass was carried out. Two-component nanocomposite films were obtained by simultaneous vacuum co-condensation of the ChGs components and organic dye on the substrate surface. The spatial arrangement of the two evaporators and substrates in a vacuum chamber allowed obtain samples with varied composite ratio. ChGs films optical band gap values were not sufficiently changed with growth rate and films thickness. It was shown that in case of dye concentration reduction for more than three orders specific absorption per dye molecule will be decreased by two orders. At greater concentrations solid solution of dye is clusterized, dye is distinctly aggregated and the absorbance is nearly the same as of the pure dye in the form of thin film. Therefore composite properties changes from cluster solution into molecular solution and thus dye molecule absorbance decrease. Relation of specific dye absorption on composite concentration was explained as electrons exchange with donor and acceptor subsystems and corresponding electron levels population. Sketch of electron density diagrams and corresponding bonds schema for composites are presented.     

Electrical conductivity of CuI-AsI<Subscript>3</Subscript>-As<Subscript>2</Subscript>Se<Subscript>3</Subscript> and CuI-SbI<Subscript>3</Subscript>-As<Subscript>2</Subscript>Se<Subscript>3</Subscript> chalcogenide films prepared by chemical deposition

The electrical conductivity of chalcogenide semiconductor films in the CuI-AsI₃-As₂Se₃ and CuI-SbI₃-As₂Se₃ systems, which have been prepared by chemical deposition from mono-n-butylamine, has been studied as a function of the temperature and film composition. It has been established that the electrical conductivity of the CuI-AsI₃-As₂Se₃ and CuI-SbI₃-As₂Se₃ films is predominantly determined by the copper iodide content. It has been demonstrated that the electrical properties of the chalcogenide glasses and the related films are characterized by the same values to within the experimental error, which is explained by the same model of dissolution of vitreous semiconductors in amines with the retention of the electrical properties of chalcogenide glasses after the deposition of films from their solutions.     

Magneto‐optical effects of Ge‐Ga‐Sb(In)‐S chalcogenide glasses with diamagnetic responses

The Faraday effects of Ge‐Ga‐Sb(In)‐S serial chalcogenide glasses were investigated at the wavelengths of 635, 808, 980, and 1319 nm, respectively. The compositional dependences were analyzed and associated influencing factors including the absorption edge, the concentration of Sb³⁺/In³⁺ ions, and the wavelength dispersion of refraction index were discussed. 80GeS₂·20Sb₂S₃ composition glass was found to have the largest Verdet constant (V=0.253, 0.219, 0.149, and 0.065 min·G^?1·cm^?1 for wavelengths 635, 808, 980, and 1319 nm, respectively) in these glasses, which is larger than that of commercial diamagnetic glasses (Schott, SF 6, V=0.069 min·G^?1·cm^?1@633 nm, for example). Sb³⁺ ions with high polarizability possessing s²‐sp electron jumps involving ¹S₀→¹P₁, ³P_0,1,2 transitions are responsible for large Verdet constant, and Becquerel rule is proved to be an effective guidance for estimating the Verdet constant and further optimizing the compositions in chalcogenide glasses.     

Broadband mid-infrared emission from Cr2+ in crystal-in-glass composite glasses by Hot Uniaxial Pressing

Cr²⁺-doped II-VI crystals have witnessed an excellent gain media for continuously tunable and femtosecond-pulsed lasers. Despite this, major challenges persist toward realizing ultrabroad emission bandwidth and efficient Cr²⁺-doped fiber due to the valence diversity of Cr, especially in chalcogenide glasses. Here, we propose to prepare Cr²⁺:ZnSe/As₂S_3-xSe_x composite glasses by Hot Uniaxial Pressing (HUP), a method that sinters uniformly mixed crystal and glass powders into geometrically designed composite chalcogenide glasses. The densification of the composite glasses reached 99.88%, indicating that a few or none pores remain. Our research shows that Cr²⁺:ZnSe crystals have good performance in chalcogenide glasses, and the composite glasses have the potential to be made into mid-infrared–doped fibers. It was demonstrated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) that the composite glasses have a uniform Cr²⁺:ZnSe distribution and no crystal disintegration. The transmittance of the composite glasses was significantly improved by tailoring the refraction index. The mid-infrared (MIR) fluorescence and decay of the glasses were measured. The lattice constant was measured, calculated, and discussed to reveal the influence of sintering process on lifetime.     

Analysis of the spectroscopic parameters of chalcogenide glasses in the Ga-Ge-S: Er3+ system

The spectroscopic characteristics of chalcogenide glasses in the Ga-Ge-S: Er³⁺ system are determined. The oscillator strengths, the Judd-Ofelt intensity parameters, the probabilities of spontaneous radiative transitions, and the radiative lifetimes of levels are calculated from the absorption spectroscopy data for two series of Ga-Ge-S chalcogenide glasses doped with Er³⁺ ions. In the first series, the Er₂S₃ content is varied from 0.49 to 4.64 mol % at the fixed composition of the glass matrix (0.15Ga₂S₃ · 0.85GeS₂). In the second series, the Ga₂S₃ content is varied from 10 to 30 mol % at the fixed Er₂S₃ content (1.94 mol %). The aforementioned spectroscopic parameters are analyzed as a function of the chalcogenide glass composition. It is revealed that the values of the oscillator strengths and the probabilities of spontaneous radiative transitions in Er³⁺ ions in the chalcogenide matrix are larger than those in phosphate, germanate, and tellurite matrices.     

Correlation Between Crystallization Behavior and Network Structure in GeS2–Ga2S3–CsI Chalcogenide Glasses

Diagram of the phase transformation behavior of GeS₂–Ga₂S₃–CsI glasses is realized in this article and the structure‐property dependence of the chalcogenide glasses is elucidated using differential scanning calorimetry and Raman spectroscopy. We observe the compositional threshold of crystallization behavior locates at x = 6–7 mol% in (100?x)(0.8GeS₂–0.2Ga₂S₃)–xCsI glasses, which is confirmed by the thermodynamic studies. Structural motifs are derived from the Raman result that [Ge(Ga)S₄], [S₂GeI₂], [S₃GaI], and [S₃Ga–GaS₃] were identified to exist in this glass network. Combined with the information of structural threshold, local arrangement of these structural motifs is proposed to explain all the experimental observations, which provides a new way to understand the correlation between crystallization behavior and network structure in chalcogenide glasses.     

Mechanical properties of SPS sintered chalcogenide glass-ceramics with externally doped crystals

The low mechanical properties limit the application of chalcogenide glasses in the infrared lens. This paper proposes a general method for enhancing the mechanical strength of chalcogenide glasses. A series of GaAs crystal-doped Ge₁₀As₂₀Se₁₇Te₅₃ and ZnS crystal-doped As₂S₅ glass-ceramics were prepared by spark plasma sintering (SPS). The effects of crystal doping on the optical and mechanical properties of glass-ceramics were studied utilizing FTIR, XRD, SEM, ultramicroscopy, and Vickers hardness. The results show that adding GaAs crystal and ZnS crystal significantly improves the hardness and fracture toughness of the chalcogenide glasses. The infrared transmittance and mechanical properties can be further improved by reducing the crystal size.     

Effect of doping by transitional elements on properties of chalcogenide glasses

In present work, the results on the influence of doping by transitional elements on thermal, optical, structural and magnetic properties of chalcogenide glasses are presented.Thermal properties (T_g values for undoped and doped glasses) were studied using differential scanning calorimetry technique. Activation energy of glass transition was estimated with the use of Kissinger’s expression. Structural studies were carried with the use of Raman and infrared spectroscopy and X-ray diffraction. Radial electron distribution functions in doped and undoped bulk glasses were obtained and analyzed. In Raman spectra, main observed effect under the introduction of dopants was the change of relative concentration of main and non-stoichiometric structural units characteristic for As₂S₃ glasses. Investigation of influence of transition metals Mn-dopants on the optical properties of As₂S₃ glass was studied in mid-IR region. Pure chalcogenide glasses are diamagnetics. Introduction of transitional and rare earth impurities changes the magnetic properties of investigated chalcogenide glasses.     

Structure,stability and optical parameters of cobalt zinc borate glasses

In this study, the impact of cobalt oxide (CoO) on the structure, stability, linear and nonlinear optical parameters of B₂O₃–Na₂O–ZnO glasses was scrutinized. A series of glass system (ZnCoNaB-glasses) was successfully prepared through the melt quenching approach. Optical absorbance, reflectance, transmittance and FTIR spectroscopy were performed for all ZnCoNaB-glasses. The FTIR results showed that the BO₄ units are enhanced while nonbridging oxygens are decreased with further CoO addition. Furthermore, ZnO exists as four-coordinated [ZnO₄] units and these units decreased with further doping of CoO. These structural variations produce a decreasing impact in Urbach energy and nonlinear refractive index, meanwhile enhance the glass stability. Further, the metallization criterion (M) values indicate that our glass samples can be used for a new generation of nonlinear optical glasses. The preceding results can predict that the investigated ZnCoNaB-glasses will be utilized in versatile applications; especially optical switching and computing.     

Ionic conductivity of (As2Se3)1 ? x(AgHal)x (Hal = I, Br) nanocomposites

Nanocomposites based on chalcogenide glasses have been synthesized. A differential thermal analysis of (As₂Se₃)_{1 − x} (AgI) _x and (As₂Se₃)_{1 − x} (AgBr)x (0 ≤ x ≤ 0.5) samples has been performed. The size of nanofragments that undergo elementary structural transformations has been evaluated. The data obtained are in agreement with the evaluated sizes of X-ray coherent scattering regions. The electrical properties of the glasses under consideration have been studied using impedance spectroscopy in the temperature range 293–393 K. It has been demonstrated that the ionic component of the electrical conductivity dominates in glasses with a high content of silver halide.     

Electrical conductivity of CuI-Cu<Subscript>2</Subscript>Se-As<Subscript>2</Subscript>Se<Subscript>3</Subscript> chalcogenide films prepared by chemical deposition

The electrical conductivity of CuI-Cu₂Se-As₂Se₃ chalcogenide semiconductor films prepared through the chemical deposition from an organic solvent has been investigated as a function of the temperature and composition of the films. It has been established that the electrical properties of the chalcogenide glasses and related films are characterized by the same values within the limits of the experimental error. This result is in agreement with the model of dissolution of vitreous semiconductors in organic bases (amines), according to which the main properties of bulk (cast) chalcogenide glasses are retained in films prepared from these glasses.     

Application of the Free Volume Concept to Glasses in the Ge–As–S System

The energy of hole formation E _h, the hole volume V _h, and the fraction f _g of fluctuation free volume for glasses in the Ge–As–S system are calculated from the data on the elastic moduli, the microhardness H, and the glass transition temperature T _g. It is shown that the fraction of fluctuation free volume in ternary glasses is considerably larger than that in arsenic chalcogenide glasses. For the glasses studied, the E _h energies fall in the range 13–18 kJ/mol and the hole volumes are equal to (7–84) × 10^–6 m³/mol. The concentration dependences of the elastic moduli and the parameters of the free volume theory for glasses in the As₂S₃–GeS₂ system are less pronounced than those for glasses in the As–S system with small coordination numbers of glass-former ions. This is explained by the topological transition observed in glasses of this system at a high germanium content. It is demonstrated that the parameters of the fluctuation free volume theory are related to the characteristics of the boson peak in the Raman spectra.