Radiation Resistance and Mechanical Stability of SiO2–BaO-Based Glass Coatings for Space Solar-Cell Panels

The influence of proton irradiation (energy, 18 MeV; beam current, 300 nA) with doses of 5 × 10¹⁴, 10¹⁵, and 5 × 10¹⁵ cm^–2 on samples of SiO₂–BaO-based glass coatings is investigated. The absorption, photoluminescence, and gamma luminescence spectra of the studied samples and their microhardness are measured. It is found that proton irradiation leads to a twofold increase in the microhardness. An insignificant increase in the optical absorption is revealed in the near-ultraviolet range (200–400 nm). This increase is accompanied by a decrease in the intensity of both light scattering in the wavelength range 400–900 nm and photoluminescence. The intensity of broadband gamma luminescence with a maximum at a wavelength of 500 nm increases with increasing proton irradiation dose. This means that excitonic radiative recombination impedes the formation of structural defects and their associated color centers. The combined effect of proton irradiation and solar electromagnetic radiation (gamma and visible light rays) accompanied by temperature changes in the range 80–470 K can provide an increase in the radiation resistance and mechanical stability of glass coatings used for solar-cell panels and their longer service life even under conditions of increased solar activity.     

The Influence of Gamma Irradiation Dose on the Formation of Radiation Defects in xCu2Se · (1 – x)As2Se3 Glasses

The defects generated under exposure to gamma radiation at a temperature of 77 K in glasses lying along the xCu₂Se · (1 – x)As₂Se₃ quasi-binary join are studied by the electron paramagnetic resonance (EPR) method. The intensity of EPR signals (I) of radiation-induced defects associated with dangling bonds of atoms in the glass network is examined as a function of the gamma irradiation dose (D = 10⁴–1.5 × 10⁵ Gy). Unlike the As₂Se₃ glass, for which the signal intensity increases almost linearly with an increase in the irradiation dose, the curves I(D) for ternary glasses are characterized by saturation dependent on the copper content in the network. The saturation of the dependences I(D) at a high copper content is explained by the formation of regions with an increased Cu content and the enhancement of the electron–phonon interaction, which prevents the stabilization of dangling bonds in the glass network. The concentration of NO₂ paramagnetic molecules formed by nitrogen and oxygen uncontrollable impurities increases linearly with an increase in the irradiation dose.     

Formation of Radiation-Induced Defects in Glasses of the Copper–Arsenic–Selenium System

The defects generated under exposure to gamma and electron radiation at a temperature of 77 K in glasses lying along the Cu₂Se–As₂Se₃ quasi-binary join of the Cu–As–Se system are studied by the electron paramagnetic resonance (EPR) method. It is shown that the introduction of copper even in small amounts leads to both the disappearance of defects typical of As₂Se₃ and the formation of new defects associated with copper. The structure of the latter defects is retained over the entire composition region and under electron irradiation. The dependence of the defect concentration on the Cu₂Se content in the glass reaches saturation at high copper concentrations. Manganese impurities compensate for dangling bonds of defects and, thus, decrease their concentration. Exposure to gamma irradiation brings about the formation of NO₂ paramagnetic molecules from nitrogen and oxygen uncontrollable impurities contained in some glasses. Under electron irradiation, these paramagnetic molecules transform into complex defects involving two nitrogen atoms located in nonequivalent positions.     

Kinetics and Mechanism of the Interaction of Alkali Calcium Silicate Glasses with Salt Melts in the KNO3–Pb(NO3)2 System

The interaction of alkali calcium silicate glasses with salt melts in the KNO₃–Pb(NO₃)₂ system is investigated at temperatures of 420–520°C. The chemical composition of crystalline coatings formed upon treatment contains both components of the initial glass (SiO₂, 9–12 wt %; CaO, 0.8–1.2 wt %) and components of the salt melt (PbO, 82–89 wt %). The treatment temperature is the main factor affecting the structure of the modified surface layer. The mechanism of the interaction of alkali calcium silicate glasses with salt melts is analyzed. According to this mechanism, the interaction involves the ion exchange (with the participation of Na⁺, K⁺, Ca²⁺, and Pb²⁺ ions), crystallization of modified surface layers, and incorporation of Pb _x O _y nanoparticles (formed in the salt melt) into the coating structure.     

Enhancement of the radiation resistance of cerium-containing fluorophosphate glasses through codoping with Sb2O3 and Bi2O3

The growing demand for radiation-resistant optical glasses for space and nuclear radiation applications has attracted significant research interest. However, radiation-resistant fluorophosphate glasses have been poorly studied. In this work, we report on the tailoring and performance of radiation-resistant fluorophosphate glasses that contained cerium through codoping with Sb₂O₃ and Bi₂O₃. The physical properties, optical properties, microstructure, and defects of fluorophosphate glasses were investigated using transmittance measurements, absorption measurements, as well as Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) spectroscopy. The results showed that the radiation resistance of all codoped fluorophosphate glasses was better than the undoped cerium-containing fluorophosphate glasses after 10–250 krad(Si) irradiation. Especially in glasses doped with Bi₂O₃, the optical density increment at 385 nm was only 0.1482 after 250 krad(Si) irradiation. The CeO₂ prevented the development of phosphate-related oxygen hole center (POHC) defects, whereas further codoping with Bi₂O₃ suppressed the formation of oxygen hole center (OHC) and POEC defects, reducing the breaking of phosphate chains caused by CeO₂. Bi³⁺ is more likely than Sb³⁺ to change the valence, affecting the transition equilibrium of intrinsic defects and reducing the concentration of defects produced by irradiation. When codoping with Sb₂O₃ and Bi₂O₃, Bi₂O₃ does not enhance radiation resistance owing to the scission effect of Sb₂O₃ on the phosphate chain, which is not conducive to the radiation resistance of glasses. This indicates that the cerium-containing fluorophosphate glasses doped with Bi₂O₃ can effectively suppress the defects caused by irradiation and improve the radiation resistance of the 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.     

Synthesis and Properties of Glasses in the NaF–ZnSO4 System

The glass-forming ability is studied in the NaF–ZnSO₄ system. It is revealed that, when melts are cooled at a rate of 10³ K/s, the glass formation is observed in the concentration range 35–70 mol % ZnSO₄. The characteristic temperatures are determined by differential thermal analysis. According to these temperatures, fluorosulfate glasses can be assigned to low-melting glasses. The density of glasses is measured by hydrostatic weighing. The experimental data obtained are used to calculate the molar volume and the thermal stability parameters of fluorosulfate glasses.     

Physical and Mechanical Properties of Neodymium Doped Zinc Borate Glass with Different Boron Content

A zinc borate glass system of composition xNa₂O-(58-x)B₂O₃-40ZnO-2Nd₂O₃(where x = 0, 5, 10, 15, 20 and 25) has been prepared using the melt quenching method. The effect of Na₂O on the crystal structure, density, molar volume and mechanical properties was investigated. X-ray diffraction analysis confirmed the amorphous nature of the prepared glass. The density and molar volume followed the normal behavior of a glass system. Ultrasonic non-destructive testing was employed for measuring the mechanical properties of the zinc borate glass system. The values of Young’s modulus and the Poisson ratio decreased with increasing the Na ⁺ concentration. Meanwhile, the microhardness, Debye temperature and acoustic impedance were diminished with increasing the Na ⁺ ion content. The results showed that the ultrasonic non destructive test measured the mechanical properties of the glass with similar accuracy to the Vickers microhardness. Such tested properties can be applied for silicate and non-silicate glasses.     

The role of MgO on the structural properties of CaO–Na2O(MgO)–P2O5–CaF2–SiO2 derived glass ceramics

The effect of increasing MgO/Na₂O replacements (on mole basis) on the crystallization characteristics of glasses based on the CaO–Na₂O(MgO)–P₂O₅–CaF₂–SiO₂ system were studied by using DTA, XRD, and SEM. The crystallization characteristics of the glasses, the type of crystalline phases formed and the resulting microstructure were investigated. The main crystalline phases formed after controlled heat-treatment of the base glass were diopside, wollastonite solid solution, fluoroapatite and sodium calcium silicate phases. The increase of MgO at the expense of Na₂O led to decrease the amount of sodium calcium silicate phase. The Vicker's microhardness values (5837–3362 MPa) of the resulting glass–ceramics were markedly improved by increasing the MgO-content in the glasses. The obtained data were correlated to the nature and concentration of the crystalline phases formed and the resulting microstructure.     

Optical,Spectral, and Radiation-Shielding Properties of High-Lead Phosphate Glasses

The spectral, optical, physicochemical, radiative, and radiation-shielding properties of glasses in the PbO-P₂O₅-R _m O _n system (where R _m O _n stands for Group I–V element oxides) are investigated as a function of their composition. The composition of a colorless radiation-resistant high-lead glass suitable for production on a semicommercial scale is determined. The properties and optical quality parameters of the glass are studied. The new phosphate glass is a lead metaphosphate containing aluminum, alkali, and alkaline-earth oxides. This glass is resistant to radiation at doses up to 10⁷ R and has an optical transmission edge at 360 nm. The coefficient of absorption of gamma radiation for the new glass is larger than those of dense silicate flints. According to the optical parameters, the new glass lies between dense flints and dense barium flints in the Abbe diagram and compensates for the absence of the latter flints in catalogues of radiation-resistant glasses.     

IR spectroscopic investigation of interaction between sodium aluminosilicate electrode glasses and aqueous solutions

The effect of introduction of aluminum oxide into the composition of sodium silicate glasses has been studied by IR absorption and reflection spectroscopy. The change in the spectroscopic characteristics of glasses after their treatment with HNO₃ and AgNO₃ aqueous solutions is analyzed. The concentration profiles of Na₊ and Ag₊ ions in the surface layers of these glasses are determined by the HF-sectioning technique. It is found that silver ions predominantly interact with the [AlO_4/2]^- groups in the glass. The leaching of sodium ions, formation of amorphous silica in the surface layers of the treated glass samples, and exchange of sodium ions by hydrogen ions are revealed from changes in the spectra.     

Specific Features of the Induced Absorption Spectra of Fluoroaluminate Glasses Doped with Samarium Ions

The induced optical absorption spectra of -irradiated fluoroaluminate glasses doped with Eu³⁺ and Sm³⁺ ions are investigated. It is shown that Sm³⁺ ions in fluoroaluminate glasses are protector ions contributing to the suppression of induced absorption in the optical absorption spectra of the studied glasses. It is revealed that the induced optical absorption spectra of the glass samples heat treated at T = 583°C contain two absorption bands with maxima at 300 and 480 nm, which correspond to radiation-reduced (Sm³⁺)^–. The concentration of color centers produced by -radiation in fluoroaluminate glasses is estimated. It is demonstrated that prolonged heat treatment of the glass at T = 638 K brings about the decay of (Sm³⁺)^– centers followed by the destruction of the samples.     

IR spectroscopic investigation of interaction between sodium aluminosilicate electrode glasses and aqueous solutions

The effect of introduction of aluminum oxide into the composition of sodium silicate glasses has been studied by IR absorption and reflection spectroscopy. The change in the spectroscopic characteristics of glasses after their treatment with HNO₃ and AgNO₃ aqueous solutions is analyzed. The concentration profiles of Na₊ and Ag₊ ions in the surface layers of these glasses are determined by the HF-sectioning technique. It is found that silver ions predominantly interact with the [AlO_4/2]^- groups in the glass. The leaching of sodium ions, formation of amorphous silica in the surface layers of the treated glass samples, and exchange of sodium ions by hydrogen ions are revealed from changes in the spectra.     

Glass Formation and Properties of Glasses in the PbO–ZnO–B2O3System

Glasses in the PbO–ZnO–B₂O₃system with a lead oxide content of less than 65 mol % are studied. The glass formation region for these glasses is determined. Their crystallization ability, density, and moisture resistance and the thermal, optical, and electrical properties are investigated. The composition–property curves are constructed. It is found that these dependences exhibit anomalies for glasses along the composition joins with constant boron oxide contents of 40 and 50 mol %. These anomalies can be associated with the change in the role of lead ions in the glass structure.     

Optical Properties and Effect of Gamma Irradiation on Bismuth Silicate Glasses Containing SrO, BaO or PbO

Optical and FT Infrared spectroscopic measurements have been utilized to investigate and characterize binary bismuth silicate glass together with derived samples by replacements of parts of the Bi₂O₃ by SrO, BaO, or PbO. This study aims to justify and compare the spectral and shielding behavior of the studied glasses containing heavy metal ions towards gamma irradiation. The study also aims to measure or calculate the optical energy band gap of these glasses. The replacements of parts of Bi₂O₃ by SrO, BaO or PbO caused some changes within the optical and infrared absorption spectra due to the different housing positions and physical properties of the respective divalent Sr2+, Ba2+, Pb2+ ions. The stability of both the optical and infrared spectra of the studied bismuth silicate glass and related samples towards gamma irradiation confirm some shielding behavior of the studied glasses and their suitability as radiation shielding candidates.     

Structure and Physicochemical Properties of Glasses in the Li2S–LiPO3 System

The temperature–concentration dependence of the electrical conductivity of glasses in the Li₂O–LiPO₃ and Li₂S–LiPO₃ systems is investigated. With the use of the Tubandt method, it is demonstrated that the electric current in glasses of these systems is provided by migration of lithium ions. The concentration dependence of the electrical conductivity is interpreted using the obtained data on the IR absorption spectra, density, microhardness, ultrasonic velocity, etc. It is found that the electrical conductivity of glasses in the Li₂S–LiPO₃ system is more than 10³ times higher than that in pure LiPO₃. The observed increase in the electrical conductivity is explained by the formation of sulfur-containing polar structural–chemical groupings of the Li⁺[S^–PO_3/2] type, whose dissociation energy is lower than that of similar oxide polar structural fragments. This results in an increase in the number of lithium ions involved in the electricity transport due to an increase in the degree of dissociation of polar structural–chemical units.     

Investigation of the Mechanism of Charge Carrier Migration in Glasses of the Li2O–P2O5 and LiF–LiPO3 Systems

The activation volumes calculated from the experimental data on the effect exerted by high hydrostatic pressure on the electrical conductivity are compared with the mean fluctuation-microhole volumes calculated from the data on the microhardness of glasses in the Li₂O–P₂O₅ and LiF–LiPO₃ systems. The fluctuation-microhole volumes determined from the microhardness are compared with the molar volumes of defects in the structure of glasses. The results obtained indicate that the defect formation occurs according to Frenkel, whereas migration of ions (charge carriers) proceeds predominantly through the interstitial mechanism, which agree with the available data.     

The dissolution behavior in alkaline solutions of a borosilicate glass with and without P2O5

There are a variety of applications for glasses in alkaline environments, including glass fibers and glass‐coated steel to reinforce concrete structures. To understand how a simple glass reacts in such environments, the dissolution behavior of a 25Na₂O–25B₂O₃–50SiO₂ (mol%) glass, doped with and without 3 mol% P₂O₅, in pH 12 KOH and pH 12 KOH saturated with Ca²⁺ ions was studied. Ca²⁺ ions in the solution significantly reduce the glass dissolution rate by forming a passivating calcium silicate hydrate (C–S–H) gel layer on the glass surface. When these corroded glasses were then exposed to Ca‐free KOH, the C–S–H layer redissolves into the undersaturated solution and the glass dissolution rate increases. For phosphate‐doped borosilicate glass, PO₄^3? units released from the dissolving glass react with Ca²⁺ ions in saturated solutions to form crystalline hydroxylapatite on the glass surface, but this layer does not protect the glass from corrosion as well as the C–S–H does. The nature of the C–S–H layer was characterized by Raman spectroscopy, which reveals a gel layer constituted mainly of silicate anions.     

Properties of RO-Y2O3-Al2O3-SiO2 glasses

The coefficient of linear expansion, glass-transition temperature, temperature at the orset of deformation (strain point), density. Young modulus, microhardness, crystallizability, and contact angle are studied as a function of the composition in RO–Y₂O₃–Al₂O₃–SiO₂ (R=Ca and/or Mg) glass systems. The composition ranges for glasses (with strain point >900°C and coefficient of linear expansion of (32–45)×10^–7°C^–1) that can be used for soldering silicon-nitride ceramics were established.Translated from Steklo i Keramika, No. 12, pp. 5–7, December, 1996     

Enhancement of UV laser-induced damage resistance of the fluoride-containing phosphate glasses by regulating the intrinsic defects

Low fluorine content containing fluorophosphate glasses have promising potential as ultraviolet (UV) optics to be used in high-energy laser systems. Systematic studies on the iron-doped and iron-free fluoride-containing phosphate glasses that were prepared at high and low melting temperatures explore the underlying interrelationship among the glass preparation conditions, intrinsic defects in produced glasses, and the anti-laser-damage properties. For the iron-doped fundamental frequency (1ω) absorptive glass, melting at high-temperature (1200°C) can reduce the extrinsic “impurity” concentration of Fe³⁺ ions, resulting in tiny increase of optical bandgap (by 1.6%) but significant reduce of the absorption coefficient by 34% at 355 nm. However, only tiny increase of the laser-induced damage threshold (LIDT) was achieved. For the iron-free third harmonic frequency (3ω) transparent glass, low-temperature (1000°C) melting process significantly reduced the absorptive intrinsic defects content of PO₃-EC, PO₄-EC, and phosphorous oxygen-bonded hole center defects, which made the UV absorption edge blue-shifted by 50 nm and the optical bandgap increased by ∼18%. The UV (355 nm) LIDT was significantly enhanced by ∼27%. Much lower absorption coefficient and larger bandgap of the iron-free glass relative to the iron-doped one endow it with larger a LIDT. In short, optimizing the glass melting temperature is a feasible method to enhance the UV laser-induced damage resistance of the fluoride-containing phosphate glasses through controlling the content of the extrinsic or intrinsic defects in produced glasses. The general routine is to achieve both the lower UV absorptive defect concentration (i.e., lower UV absorption at 355 nm) and the lower non-bridged oxygen ratio (i.e., denser glass network), as well as a larger optical bandgap (i.e., reduced probability of avalanche ionization breakdown), which together contribute to the enhancement of the anti-laser-damage performance of the investigated fluoride-containing phosphate glasses.