Ga2S3‐Sb2S3‐CsI chalcohalide glasses for mid‐infrared applications

In this study, a new chalcohalide glass system, Ga₂S₃‐Sb₂S₃‐CsI, is reported. It has a glass‐forming domain composed of ~0‐35 mol% Ga₂S_3, ~15‐95 mol% Sb₂S₃, and ~0‐55 mol% CsI. The glasses have a wide transparent window of ~0.7‐13.5 μm, high third‐order nonlinear refractive indices of ~1.7‐8.7×10^?14 cm²/W @ 1.55 μm, and relatively short zero group‐velocity‐dispersion wavelengths of 3.8‐5.15 μm. The glasses can dissolve more than 2 mol% active ions (e.g., Dy³⁺), and the doped glasses show intense emissions in the mid‐infrared. These superior properties demonstrate their good potentials for mid‐infrared applications such as thermal imaging, nonlinear photonics and lasers.     

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.     

Dy3+‐Doped Selenide Chalcogenide Glasses: Influence of Dy3+ Dopant‐Additive and Containment

This work reports on process‐induced impurities in rare‐earth ion: Dy³⁺‐doped selenide chalcogenide glasses, which are significant materials for active photonic devices in the mid‐infrared region. In particular, the effect of contamination from the silica glass ampoule containment used in chalcogenide glass synthesis is studied. Heat‐treating Dy‐foil‐only, and DyCl₃‐only, separately, within evacuated silica glass ampoules gives direct evidence of silica ampoule corrosion by the rare‐earth additives. The presence of [Ga₂Se₃] associated with [Dy] on the silica glass ampoule that has been contact with the chalcogenide glass during glass melting, is reported for the first time. Studies of 0–3000 ppmw Dy³⁺‐doped Ge_16.5As₉Ga₁₀Se_64.5 glasses show that Dy‐foil is better than DyCl₃ as the Dy³⁺ additive in Ge‐As‐Ga‐Se glass in aspects of avoiding bulk crystallization, improving glass surface quality and lowering optical loss. However, some limited Dy/Si/O related contamination is observed on the surfaces of Dy‐foil‐doped chalcogenide glasses, as found for DyCl₃‐doped chalcogenide glasses, reported in our previous work. The surface contamination indicates the production of Dy₂O₃ and/or [≡Si‐O‐Dy=]‐containing particles during chalcogenide glass melting, which are potential light‐scattering centers in chalcogenide bulk glass and heterogeneous nucleation agents for α‐Ga₂Se₃ crystals.     

The influence of different antimony content in Ga-As-Sb-S chalcogenide glass system: Modification of physical & spectroscopic properties and fiber forming ability

In order to improve the fiber drawing performances including the anti-crystallization in fiber drawing process and the mechanical properties, the fourth component of antimony (Sb) was introduced into Ga_0.8As_39.2S₆₀ glass, and a serial Ga_0.8As_39.2-xSb_xS₆₀ (x = 0, 1, 3,5, 7, 9 and 11) novel chalcogenide glasses doped with 3000 ppmw Dy³⁺ ions were prepared. The influences of antimony content on the physical properties, spectroscopic properties and fiber forming ability of glass were investigated. The experiment results indicate that the introduction of moderate antimony into glass effectively improves the fiber drawing performance and the spectroscopic properties of Dy³⁺ ions. The Ga_0.8As_34.2Sb₅S₆₀ composition glass possesses the best performance and it is recommended a good candidate for mid-infrared laser working medium.     

First Identification of Rare‐Earth Oxide Nucleation in Chalcogenide Glasses and Implications for Fabrication of Mid‐Infrared Active Fibers

Gallium (Ga) helps solubilize rare‐earth ions in chalcogenide glasses, but has been found to form the dominant crystallizing selenide phase in bulk glass in our previous work. Here, the crystallization behavior is compared of as‐annealed 0–3000 ppmw Dy³⁺‐doped Ge–As–Ga–Se glasses with different Ga levels: Ge_16.5As_(19?x)Ga_xSe_64.5 (at.%), for x = 3 and 10, named Ga₃ and Ga₁₀ glass series, respectively. X‐ray diffraction and high‐resolution transmission electron microscopy are employed to examine crystals in the bulk of the as‐prepared glasses, and the crystalline phase is proved to be the same: Ge‐modified, face centered cubic α‐Ga₂Se₃. Light scattering of polished glass samples is monitored using Fourier transform spectroscopy. When Ga is decreased from 10 to 3 at.%, the bulk crystallization is dramatically reduced and the optical scattering loss decreases. Surface defects, with a rough topology observed for both series of as‐prepared chalcogenide glasses, are demonstrated to comprise Dy, Si, and [O]. For the first time, evidence for the proposed nucleation agent Dy₂O₃ is found inside the bulk of as‐prepared glass. This is an important result because rare‐earth ions bound in a high phonon–energy oxide local environment are, as a consequence, inactive mid‐infrared fluorophores because they undergo preferential nonradiative decay of excited states.     

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.     

Optical Property of Dy3+‐and Ce3+‐Doped Si–B–Na–Sr Glasses

Novel Dy³⁺ and Ce³⁺ doped Si–B–Na–Sr (SBNS) glasses were synthesized by melt‐quenching technique. Excited by 327 nm, the 0.5Dy³⁺‐and 0.5Ce³⁺‐doped SBNS exhibits white emission with Commission Internationale de L'Eclairage coordinates of (0.308, 0.280). Basic optical characterizations have been performed by measuring the absorption and emission spectra and calculating Judd–Ofelt intensity parameters, radiative probability, luminescence branching ratio, cross sections, and effective bandwidth. The Judd–Ofelt parameters Ω₂, Ω₄, and Ω₆ indicate a high asymmetrical environment and covalent environment in the optical glass. The emission color of Ce³⁺ and Dy³⁺ codoped transparent glass can be tuned from blue to white through energy transfer from Ce³⁺ to Dy³⁺ ions. The resulting glass may have potential application in white‐light‐emitting source.     

Enhanced Thermostability,Thermo‐Optics,and Thermomechanical Properties of Barium Gallo‐Germanium Oxyfluoride Glasses and Glass‐Ceramics

Serial substitutions of BaF₂ for BaO in BaO–Ga₂O₃–GeO₂ glasses were performed, and the effects of the substitutions on the glass properties were investigated. The glass transition temperature, density, refractive index, thermo‐optics coefficient, and figure of merit for thermal shock decreased with the replacement of oxygen by fluorine. On the other hand, the glass‐forming ability increased. Fluorine substitution removed the absorption band of hydroxyl near 2.9 μm. Raman scattering spectroscopy was used to characterize the fluorogermanate glasses. The crystallization process of the glass‐ceramics under different heat‐treatment conditions was also investigated using differential scanning calorimetry, X‐ray diffraction, scanning electron microscopy, and atomic force microscopy. The thermal and mechanical properties were improved by controlling the crystal size of the near‐ and middle‐infrared transparent glass‐ceramics.     

Ce3+‐ and Dy3+‐Doped Oxyfluoride Borosilicate Glasses with Near White Luminescence

A series of Ce³⁺/Dy³⁺‐doped oxyfluoride borosilicate glasses prepared by melt‐quenching method are investigated for light‐emitting diodes applications. These glasses are studied via X‐ray diffraction (XRD), optical absorption, photoluminescence (PL), color coordinate, and Fourier transform infrared (FT‐IR) spectra. We find that the absorption and emission bands of Ce³⁺ ions move to the longer wavelengths with increasing Ce³⁺ concentrations and decreasing B₂O₃ and Al₂O₃ contents in the glass compositions. We also discover the emission behavior of Ce³⁺ ions is dependent on the excitation wavelengths. The glass structure variations with changing glass compositions are examined using the FT‐IR spectra. The influence of glass network structure on the luminescence of Ce³⁺/Dy³⁺ codoped glasses is studied. Furthermore, the near‐ideal white light emission (color coordinate x = 0.32, y = 0.32) from the Ce³⁺/Dy³⁺ codoped glasses excited at 350 nm UV light is realized.     

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.     

The Effect of PbS on Crystallization Behavior of GeS2‐Ga2S3‐Based Chalcogenide Glasses

Glass‐ceramics of PbS‐doped 80GeS₂·20Ga₂S₃ were fabricated by heat treatments of base glasses at T_g+30°C for different durations. They exhibited improved mechanical properties such as hardness and resistance to crack propagation, and meanwhile retained their excellent infrared transmission. X‐ray diffraction and Raman results indicated that Ga₂S₃ and GeS₂ crystals were precipitated inside glassy matrix. The crystallization kinetics of base glass was investigated using differential scanning calorimetry under nonisothermal conditions. Compared with the previous work concerning on 80GeS₂·20Ga₂S₃ glass, there exists some different features of crystallization behavior. Such variation is discussed and correlated with the network structure and crystallization kinetics in this glass system.     

Formation of Ferroelectric Phases in Sb–S–I Glasses

We have investigated devitrification of glasses within infrared transmitting xSbSI–(100 ? x)Sb₂S₃ pseudo‐binary series, which forms SbSI and Sb₂S₃ ferroelectric crystal phases. Differential scanning calorimetry (DSC) and X‐ray powder diffraction results show unusual behavior for the formation of the SbSI phase, which occurs by two parallel processes: one‐dimensional crystallization at low temperature which starts from the sample surface, and three‐dimensional bulk crystallization that continues the transformation to crystalline state at higher temperatures. The ratio of the intensities of the high‐temperature exothermal peak to the low‐temperature peak in DSC scans increases as the particle size and heating rate are increased. In contrast to the SbSI phase, the temperature of crystallization for the Sb₂S₃ phase does not depend on the particle size. Models are proposed for the origin of the various crystallization mechanisms.     

Thermal and optical properties of La2O3–Ga2O3– (Nb2O5 or Ta2O5) ternary glasses

La₂O₃–Ga₂O₃–M₂O₅ (M = Nb or Ta) ternary glasses were fabricated using an aerodynamic levitation technique, and their glass‐forming regions and thermal and optical properties were investigated. Incorporation of adequate amounts of Nb₂O₅ and Ta₂O₅ drastically improved the thermal stabilities of the glasses against crystallization. Optical transmittance measurements revealed that all the glasses were transparent over a wide wavelength range from the ultraviolet to the mid‐infrared. The refractive indices of the glasses increased and the Abbe number decreased upon substituting Ga₂O₃ with Nb₂O₅, and the decrease in the Abbe number was significantly suppressed when Ta₂O₅ was incorporated into the glass. As a result, excellent compatibility between high refractive index and lower wavelength dispersion was realized in La₂O₃–Ga₂O₃–Ta₂O₅ glasses. Analysis based on the single‐oscillator Drude–Voigt model provided more systematical information and revealed that this compatibility was due to an increase in the electron density of the glass.     

2.5–5.5 μm mid-infrared emission from Ni2+-doped chalcohalide glass ceramics containing CsPbI3 perovskite nanocrystals

The development of mid-infrared (MIR) broadband tunable lasers urgently needs high performance laser gain materials. Transition metal (TM) ions doped glass ceramics are considered to be efficient MIR broadband laser gain media. However, it is difficult to achieve gain because of the large scattering loss and low luminescence efficiency. In this paper, GeS₂–Sb₂S₃–CsI–PbI₂ chalcohalide glass ceramics containing CsPbI₃ perovskite nanocrystals are fabricated by the melt-quenching method and subsequent heating treatment. The crystallization behavior of CsPbI₃ nanophase and MIR luminescence properties of Ni²⁺ dopant are systematically investigated. Evidently, spherical CsPbI₃ perovskite nanocrystals are precipitated and uniformly distributed in the glassy matrix, which can reduce the light scattering and make the chalcohalide glass ceramics have a high transparency. Moreover, an ultra-broadband MIR emission in the range of 2.5–5.5 μm is observed for the first time, to our best knowledge, from Ni²⁺-doped chalcohalide glass ceramics containing CsPbI₃ perovskite nanocrystals. The newly developed Ni²⁺-doped chalcohaldie glass ceramics could be promising gain media for MIR broadband tunable lasers.     

Investigation of the Ga-Sb-S chalcogenide glass with low thermo-optic coefficient as an acousto-optic material

In this study, two series of Ga_xSb_40-xS₆₀ (x = 4, 6, 8, 10 mol%) and Ga_ySb₃₆S_64-y (y = 3, 5, 6 mol%) glasses were prepared and the relationship between their compositional and acousto-optic (AO) properties was investigated systematically for the first time. In the Ga_ySb₃₆S_64-y system, the AO figure of merit (M₂) increased as the Ga increased, and the maximum M₂ of the Ga₆Sb₃₆S₅₈ glass was 455.78 × 10^?18 s³/g, which is ～301 times greater than that of fused silica and ～2.5 times greater than that of As₂S₃ chalcogenide (ChG) glass at 1550 nm. However, its thermo-optic coefficients (dn/dT) varied greatly (32.1 × 10^?6 °C^?1–57.2 × 10^?6 °C^?1), and acoustic attenuations (α) at 10 MHz were high, from 5.446 dB/cm to 7.274 dB/cm. In the Ga_xSb_40-xS₆₀ glass system, the M₂ value and α at different ultrasonic frequencies gradually decreased with the improvement of Ga. Compared with the Ga_ySb₃₆S_64-y system, the Ga_xSb_40-xS₆₀ glass system had lower α (at 10 MHz) and dn/dT, which are 5.001 dB/cm–5.563 dB/cm and 17.3 × 10^?6 °C^?1–55.6 × 10^?6 °C^?1, respectively. These results provide a significant reference for the further development of novel ChG glasses and help expand their application fields.     

Controllable Formation of the Crystalline Phases in Ge–Ga–S Chalcogenide Glass‐Ceramics

We prepared chemically stoichiometric, S‐poor and S‐rich Ge–Ga–S glasses and annealed them at a temperature that was 20°C higher than its respective glass transition temperature. We aimed at tuning the formation of the different crystals in chalcogenide glass‐ceramics. Through systematic characterization of the structure using X‐ray diffraction and Raman scattering spectra, we found that, GeS₂ and GeS crystals only can be created in S‐rich and S‐poor glass‐ceramics, respectively, while all GeS, Ga₂S₃, and GeS₂ crystals exist in chemically stoichiometric glass‐ceramics. Moreover, we demonstrated the homogeneous distribution of the crystals can be formed in the S‐rich glass‐ceramics from the surface to the interior via composition designing. The present approach blazes a new path to control the growth of the different crystals in chalcogenide glass‐ceramics.     

Glass Formation and Ionic Conduction Behavior in GeSe2–Ga2Se3–NaI Chalcogenide System

Series of glassy and glass‐ceramic samples in the GeSe₂–Ga₂Se₃–NaI system is prepared by melt‐quenching technique and the glass‐forming region is well‐defined by XRD investigations. Na‐ion conduction behavior is systemically studied by impedance measurements. For the glasses in the series (100?2x)GeSe₂–xGa₂Se₃–xNaI, ionic conductivities increased with increasing x, whereas the attributed activation energy of ion conduction decreases. The enhanced mechanism is discussed by employing Raman spectra. In addition, the effect of the crystal phases NaI and Ga₂Se₃ on the ionic conduction behavior in the (70?x)GeSe₂–xGa₂Se₃–30NaI samples is discussed. Although it shows that the poorly conducting crystallites of NaI and Ga₂Se₃ have a negative effect on the ionic conductivities in this series, the highest ionic conductivity of 1.65 × 10^?6 S/cm is obtained in the 45GeSe₂–25Ga₂Se₃–30NaI glass. Finally, this study also demonstrates a possible way to search appropriate Na‐ion solid electrolytes for all‐solid‐state batteries.     

Ga–Sb–S Chalcogenide Glasses for Mid‐Infrared Applications

In this study, a novel chalcogenide glass system, Ga–Sb–S, is reported. The glass‐forming ability, the physical properties, and the structure are investigated; and the potential applications of the glasses are evaluated. The compositions consisting of ~3%–10% Ga, ~29%–37% Sb, and ~57%–63% S can form glasses. The glasses have a wide transparent window of ~0.8–14 μm, high linear refractive indices of ~2.62–2.70 (@10 μm), high third‐order nonlinear refractive indices of ~12.4 × 10^?14 cm²/W (@ 1.55 μm), low phonon energy, and large rare earth solubility. These favorable properties make them promising materials for mid‐infrared applications such as thermal imaging, nonlinear optics, and lasers.     

Physicochemical and optical properties of glasses in the Ga<Subscript>4</Subscript>Ge<Subscript>21</Subscript>Se<Subscript>50</Subscript>-Sb<Subscript>2</Subscript>Se<Subscript>3</Subscript> system

This paper reports on the results of an investigation into the concentration behavior of the glass-forming ability, heat resistance, glass transition temperature, density, refractive index, transparent spectral region, and impurity optical absorption of glasses in the Ga₄Ge₂₁Se₅₀-Sb₂Se₃ system. The data obtained indicate that glasses in the Ga₄Ge₂₁Se₅₀-Sb₂Se₃ system with a high Sb₂Se₃ content are of interest as materials for use in fiber optics.     

Physicochemical and optical properties of glasses in the Ga4Ge21S50-Sb2S3 system

This paper reports on the results of an investigation into the influence of Sb₂S₃ dopants on the glass-forming ability, heat resistance, softening temperature, density, refractive index, transparent region, and impurity optical absorption of glasses of the composition 0.16GaS₂ · 0.84GeS₂. The data obtained indicate that glasses in the Ga₄Ge₂₁S₅₀-Sb₂S₃ system with a high Sb₂S₃ content are of interest as materials for use in fiber optics.