ABSTRACT An inverse, reversible thermochromic K 2 O·nSiO 2 ‐based fire‐resistant glass was developed through a low‐temperature in situ reaction using NH 4 HCO 3 as a multifunctional additive. The glass changed from white and opaque at room temperature (∼20–25°C) to colorless and transparent at ∼60°C, reaching a transmittance of 90.51 ± 0.32% and maintaining stable thermochromic behavior over 1000 thermal cycles. NH 4 HCO 3 incorporation increased the compressive stress at 66.7% strain from 2.6 ± 0.1 to 6.8 ± 0.2 MPa, accompanied by enhanced silicate‐network connectivity as revealed by Raman spectroscopy. During high‐temperature exposure, NH 4 HCO 3 promoted multistage foaming and hierarchical micro‐/nanoscale pore formation within the expanded barrier layer. The resulting pore‐within‐pore architecture increased the tortuosity of heat‐transfer pathways and suppressed structural collapse. After 60 min of fire exposure, the average unexposed‐side temperature remained well below the prescribed limit of 160°C. This work provides a practical strategy for integrating adaptive optical regulation, mechanical reinforcement, and high‐temperature thermal protection within a single inorganic glass system.
ABSTRACT Ion exchange strengthening is a crucial engineering technique for enhancing the mechanical performance of glass materials. In this study, a composition‐driven ion‐exchange mapping model combined with molecular dynamics simulations was used to investigate the structural and mechanical responses of mixed alkali aluminosilicate glass at different ion‐exchanged states. Structural analysis reveals the presence of polyhedra and tricluster oxygen species, which contribute to the modification of the glass network upon ion exchange. Mean square displacement analysis confirms that alkali ion mobility follows the trend , influencing the degree of charge compensation and network rearrangement. Radial distribution function and bond angle distribution analyses indicate slight shortening of and bonds, accompanied by a reduction in the and angles, reflecting the local compressive fields of tetrahedral network. Mechanical simulations reveal that ion exchange increases the elastic modulus by roughly 10.5% and enhances surface hardness by 23.9%, accompanied by a marked improvement in tensile fracture resistance. These findings provide atomic‐level insights into the composition–structure–property relationships in ion‐exchanged glasses, offering guidance for optimizing glass strengthening processes in industrial applications.
ABSTRACT Nepheline crystallization during canister centerline cooling is one of the most constraining factors limiting waste loading in high‐level waste (HLW) borosilicate glasses. Existing predictive models treat nepheline formation as a binary outcome, yet durability degradation depends continuously on nepheline fraction. This study moves beyond binary classification by combining domain knowledge with association rule mining to extract compositional and thermal‐history rules associated with specific nepheline fraction thresholds. A physics‐based feature selection strategy reduced 70 compositional, structural, and kinetic variables to 15 features spanning the thermodynamic, charge‐compensation, modifier‐partitioning, and kinetic domains. Rules were mined from 727 quantified HLW glass compositions using three nepheline thresholds. Single‐feature and pairwise analyses reveal that the onset of nepheline formation is governed by the sodium–aluminum–boron balance and reinforced by kinetic factors, whereas the amount of nepheline, once formation has occurred, depends on the partitioning of modifier cations and the structural connectivity of the glass network. These results suggest that nepheline crystallization is governed by two mechanistically distinct processes, namely a compositionally sharp onset and a diffuse severity regime, a distinction applicable to any aluminosilicate system where nepheline amount is the target of compositional optimization.
ABSTRACT Staining of glass facades is a recurring and significant problem worldwide. This study investigates the causes of staining observed on six laminated float glass samples from four manufacturers (α, β, γ, and δ). Samples from β, γ, and δ were new, whereas those from α (α 1 , α 2 , and α 3 ) were taken from a building after service exposure. Staining of α 2 , α 3 , and δ was observed after exposure to an acid‐cleaning product for at least 30 s. Our investigation focused on tin concentration and oxidation state at the glass surface, the overall chemical composition, and surface condition as potential factors associated with this behavior. Extensive characterization using multiple techniques revealed small amounts of tin on the outer face, with the highest content in α 3 . However, neither tin concentration nor its oxidation state showed a clear correlation with the staining pattern, as α 2 and δ had much lower tin levels. The staining observed for the unused δ glass is attributed to its higher modifier content relative to network formers and lower chemical durability. In contrast, the staining observed for α 2 and α 3 appears to be related to surface damage, in which micro‐scratched surfaces undergo a rapid increase in roughness upon chemical exposure and become more susceptible to visible staining, whereas well‐polished surfaces remain largely unaffected. These results indicate that chemical durability and surface condition are important factors influencing the susceptibility of float glasses to staining.
ABSTRACT Soda lime silica (SLS) glass is a widely used material, and as such, the impact of surface treatments on the mechanical and chemical properties has been extensively studied. For example, it is well established in the literature that treating SLS in acidic solutions results in the formation of a sodium‐depleted surface layer, as sodium exchanges with hydrous species from the solution. Separately, a great deal of work has examined the impact of sub‐ T g thermal annealing on the properties of SLS and its ability to repopulate the weathered glass with sodium from the bulk and relieve residual network stress from processing. Within this work, a process is studied where SLS glass is treated with alternating steps of sub‐ T g thermal annealing and exposure to a pH 1 solution of nitric acid at 90°C. Through x‐ray photoelectron spectroscopy and surface‐sensitive vibrational spectroscopy, it was found that annealing the acid‐leached glass resulted in an approximately 10% increase in the bridging oxygen content at the surface, implying repolymerization of silanol groups formed during acid treatment. While leaching the glass completely halted cracking during Vickers indentation at 0.05 kgf, it also corresponded to a decrease in Vickers hardness by 0.15 GPa. Annealing the leached layer retained the majority of the crack resistance (95% probability of no cracks), while mitigating this decrease in hardness.
Colorless and transparent La 2 O 3 –Nb 2 O 5 –WO 3 (LNW) glasses were successfully synthesized using a levitation technique in a wide glass‐forming region. These glasses exhibited excellent optical properties, including a high refractive index (>2.1) with low wavelength dispersion, and high transmittance (70%‒75% at a thickness of ∼800 µm) in the ultraviolet–visible region. The glass transition temperature decreased with increasing WO 3 content, reaching as low as 550°C, which enables easier pressing and molding compared to other levitation‐synthesized high‐refractive‐index glasses, such as Nb 2 O 5 ‐based and TiO 2 ‐based glasses. The dependence of the packing density and the electronic polarizability of the oxide ion on the Nb 2 O 5 content suggested that the effect of substituting Nb 2 O 5 with WO 3 substantially differs between La 2 O 3 ‐rich and Nb 2 O 5 ‐rich La 2 O 3 –Nb 2 O 5 binary glasses. The inherent absorption wavelength decreased with increasing WO 3 content, resulting in a lower wavelength dispersion of the refractive index. These findings indicate that LNW glasses are promising optical materials for advanced applications requiring high refractive index and low processing temperature.
Lead‐free bismuthate‐based sealing glasses are of growing interest for environmentally sustainable electronic and packaging applications. In this work, lead‐free Bi 2 O 3 –ZnO–B 2 O 3 glasses were modified through two distinct substitution routes—BaO replacing B 2 O 3 and SrO exchanging for BaO—to evaluate their suitability for glass‐to‐metal sealing. BaO‐for‐B 2 O 3 substitution reduced glass transition temperature (330→325°C) and increased coefficient of thermal expansion (13.0→14.1 ppm/K) due to network depolymerization, yielding a low sealing range of 505–550°C, but decreasing nanohardness (4.9→4.6 GPa) and elastic modulus (69→63 GPa). SrO‐for‐BaO exchange maintained nearly constant density and mechanical properties, with only minor fluctuations in thermomechanical properties, while supporting a sealing window of 520–580°C. Raman spectra confirmed increasing nonbridging oxygen formation in BaO‐substituted glasses, whereas SrO exchange induced only subtle structural shifts. Both systems formed diffusion‐bonded interfacial layers (<2 µm) with 304 stainless steel and showed thermal expansion compatibility (mismatch <10%), validating hermetic sealing. These results establish BaO‐for‐B 2 O 3 substitution as advantageous for low‐temperature sealing and SrO‐for‐BaO exchange as beneficial for stabilizing thermomechanical properties, offering complementary design strategies for sustainable lead‐free sealing glasses.
Understanding how vanadium oxide (V2O5) influences the dissolution behavior of nuclear waste glasses is essential for optimizing their waste loading and long-term durability. In this work, a series of sodium aluminoborosilicate-based model glasses-(100-x) (30Na2O-5Al2O3-15B2O3-50SiO2)-xV2O5, where x = 0, 2.5, and 5 mol.%-were synthesized to investigate the structural and chemical origins of V2O5-dependent dissolution behavior. Glass corrosion experiments were conducted in both deionized (DI) water and 0.1 M Tris-HCl buffer (pH 7) at 65 degrees C for 7 days. The results revealed that all glasses dissolved incongruently, with Na, B, and V leaching more rapidly than Si and Al. The incorporation of V2O5 produced a statistically insignificant change in the dissolution kinetics of glasses in Tris-HCl, although dissolution in Tris-HCl was consistently faster than in deionized water. XPS and XANES analyses confirmed that vanadium exists primarily as V5+ (tetrahedral [V5+O4]3-), with a minor fraction of V4+ (square-pyramidal [V4+O5]6-). However, quantitative discrepancies between the two techniques highlight differences in their surface and bulk sensitivities. The minimal impact of V2O5 on the dissolution kinetics of glasses in Tris-HCl is rationalized by a structural model in which highly charged [V5+O4]3- units remain largely decoupled from the silicate network and scavenge Na+ from the aluminoborosilicate network for charge-compensation, leading to competing effects that offset one another during glass corrosion.
This study presents the development of fluorine-free white glass-ceramic enamel coatings from locally available Uzbek mineral raw materials, including quartz sand, clay shale, boron- and phosphorus-containing glass-forming components. The enamel frits were designed in the SiO2-Al2O3-Na2O-K2O-B2O3-TiO2-P2O5 multicomponent system by optimizing the contents of the principal glass-network-forming oxides (SiO2, B2O3, TiO2, and P2O5) while keeping the modifier content constant. After application to DC04EK steel substrates, the coatings were produced by a two-stage firing process. Their phase composition, microstructure, chemical bonding, optical behavior, and functional performance were comprehensively investigated using XRD, SEM-EDS, FTIR, UV-Vis spectroscopy, and standard mechanical and chemical resistance tests. The optimized compositions exhibited high whiteness values of up to 88.9%, excellent chemical resistance (Class AA), strong adhesion to the steel substrate, and good thermal-cycling stability. XRD confirmed the crystallization of rutile-type TiO2, while FTIR analysis confirmed the presence of a borosilicate glass network and SEM-EDS mapping demonstrated homogeneous elemental distribution within the enamel matrix. The coatings satisfied the requirements of ISO 28722:2008, confirming their suitability for practical application in household steel products. These results demonstrate that locally sourced mineral feedstocks can serve as a sustainable and cost-effective basis for the production of high-performance white glass-ceramic enamel coatings.
Four glass structures with the nominal composition (BaO)55 + (B2O3)(40-x) + (Li2O)5 + (ZrO2)x were produced via melt-quenching. Zirconium oxide at concentrations from 0 to 5 wt% was tested for radiation shielding. The densities of the generated glasses varied from 3.5261 to 3.9998 g/cm3 with the substitution of ZrO2, which is crucial for assessing radiation shielding characteristics that rose with the elevated concentration of ZrO2. The glass samples' FTIR and Raman spectra show a borate glass network and zirconium oxide inclusion, with vibrational bands that show the alternation in the [BO3]/[BO4] ratio and increasing polymerization after adding ZrO2. Increased ZrO2 concentration enhances network connection by forming BO4 units and Zr-O bonds. UV analyses clarified optical and physical properties. An increase in absorbance intensity may indicate Zr4 + ion-related defect states or scattering effects. The energy gap decreases from 3.095 eV at 0% ZrO2 to 2.924 eV at 5% ZrO2. Phy-X/PSD was used to study the radiation shielding of barium borate glasses with zirconium oxide. This approach was used to characterize photon energy-related linear attenuation coefficients, half-value layers, tenth-value layers, and effective conductivity parameters. The results demonstrate that the BBZr5 sample, containing 5 wt% of ZrO2, will be the most effective for radiation shielding. ZrO2 improved the glass's radiation shielding by increasing the linear attenuation coefficient.
Over the past few decades, tissue engineering has undergone significant advancements, enabling the development of complex and customizable synthetic tissue constructs. Among these, 3D printing has emerged as a powerful technique for fabricating scaffolds with precisely controlled architectures capable of mimicking tissue-specific mechanical and biological properties. In this context, the present study focuses on the development of a slurry-based 3D printing approach for fabricating bioactive glass scaffolds with enhanced mechanical performance tailored for site-specific tissue engineering applications. The rheological behavior of the printable viscous dough was systematically optimized to achieve superior printability and structural integrity after post-printing. Comprehensive characterization techniques, including SEM, FTIR, and TG-DSC analysis, were employed to investigate the physicochemical states of the synthesized glass particles. XRD analysis confirmed the formation of a stabilized glassy phase with enhanced ionic mobility under controlled heat treatment. The biologically active and mechanically robust scaffolds exhibited accelerated biomineralization kinetics and apatite growth on their surfaces. Thus, these findings highlight the potential of 3D-printed, customized BG scaffolds as promising candidates for promoting bone regeneration within the broader framework of regenerative medicine.
137Cs has become one of the key challenges in the dry reprocessing of spent fuel due to its poor separability and high radioactivity. The synthesis of Cs2SnCl6 for the removal of CsCl from waste salts and the preparation of Cs2SnCl6-glass composites was investigated in this study. The optimal conditions for the hydrothermal synthesis of Cs2SnCl6 are a reaction at 150 degrees C for 6 h, and XRD results indicate that the product is a pure cubic phase. CsCl is removed from LiCl-KCl-CsCl waste salts by the synthesis of Cs2SnCl6. This method enables efficient and selective separation of Cs+ from waste salts with a Cs+ content of 2.5-10 wt.%, achieving a removal efficiency of over 96%. The glass composites have a maximum embedding rate of 30 wt.%. Cs+ and Cl- are uniformly distributed in the glass matrix, and the glass matrix exhibits good compatibility with Cs2SnCl6. The PCT test showed that the normalized leaching rates of Cs+ and Cl- on the 28th day were as low as 1.6 & times;10- 4 and 3.4 & times;10- 4 g & centerdot;m- 2 & centerdot;d- 1, respectively, demonstrating that the Cs2SnCl6-glass composite exhibits excellent leaching resistance.
The intense natural resources exploitation and waste generation by the construction industry have driven the demand for more sustainable alternative materials. Thus, this study investigated the production and application of glass foams from recycled glass and rice husk ash (RHA), using calcium carbonate (CaCO3) as a foaming agent, for enhanced thermal comfort in buildings. Mixtures containing 80% recycled glass and 20% RHA were prepared with varying CaCO3 contents (0%-5%) and sintered at 950-1030 degrees C to establish optimal processing conditions. The sample sintered with 2% CaCO3 at 1000 degrees C exhibited the best performance: apparent density of 0.29 g/cm3, compressive strength of 0.81 MPa, porosity of 88.1%, and thermal conductivity of 0.1195 W/(m & centerdot;K) +/- 0.007. These values meet the standards for commercial glass foams and align with performances reported in the literature. To assess the practical thermal insulation effects, 20-mm-thick foam panels were installed as ceiling linings in a model masonry building and compared to an uninsulated control. Temperature monitoring over 8 days revealed that the foam-lined ceiling achieved larger temperature differences, particularly during peak solar exposure, confirming its efficiency in reducing heat transfer. These results demonstrate the technical feasibility and environmental relevance of producing thermal insulation materials from recycled glass and RHA for sustainable building applications.
Glasses and corresponding glass-ceramics were studied in the Na2O-V2O5-TeO2 (NVT) system. The thermal and electrical properties, as well as the structure of parent glasses, were determined by differential scanning calorimetry (DSC), electrochemical impedance spectroscopy measurements (EIS), and pair distribution function (PDF), respectively. The V4+/V5+ ratio in the parent glasses was estimated by X-ray photoelectron microscopy (XPS). While only one crystalline phase has already been discovered in the NVT system, this thorough experimental study evidences the stabilization of several novel crystalline phases through the glass crystallization process. An attempt to solve one of these structures, (Te0.66Na0.34)2V2O8, is described in the present study. The glass-ceramics were produced by the spark plasma sintering (SPS) technique and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). An overall increase in the electrical conductivity from the parent glass to its corresponding glass-ceramic is observed up to five orders of magnitude for some compositions, to be related to the microstructure and the nature of the stabilized crystalline phase.
A series of novel container glass compositions has been developed that can be melted from natural raw materials without the addition of soda ash. Each formulation contains up to 50% cullet from recycled container glass. The temperature-viscosity profiles, liquidus temperatures, electrical resistivities, and basic processability of these compositions are comparable to those of conventional soda-lime-silica glasses. Melting energy consumption is decreased, and the batch-to-melt conversion time is markedly reduced. The resulting glasses exhibit significantly lower coefficients of thermal expansion.
The responses of the quaternary lithium borosilicate glass (QBG) are systematically examined under coupled gamma-irradiation and corrosion. QBG samples were exposed to 300 kGy for 2 days and 3 MGy for 20 days, followed by analyses of pH, elemental release, optical features, and vibrational spectra. Compared with corrosion-only samples, gamma-irradiation decreased the pH of the leachate, promoting ion exchange reactions and consequently accelerating the release of Na, B, and Si, with more pronounced synergistic effects observed at higher doses and longer durations. A reduction in Q 3 species and an increase in non-bridging oxygen (NBO) content indicated changes in the Si-O-Si bond angles and a decline in network polymerization. Optical microscopy revealed bubble formation under coupled experiments, suggesting enhanced molecular oxygen generation. These results demonstrate that gamma-irradiation facilitates glass corrosion through both network depolymerization and acidification. Moreover, the structural response under coupled experiments differs significantly from that observed under single-factor treatments, underscoring the importance of accounting for irradiation-corrosion coupling when assessing the long-term geological disposal performance of vitrified waste forms.
The structure and mechanical response of peraluminous chemically strengthened lithium aluminosilicate glass under different post-annealing conditions below the glass transition temperature were investigated. Changes in surface structure and mechanical properties were evaluated based on measurements of the compressive stress, depth of layer, electron probe microanalysis, Raman spectroscopy, hardness, and coaxial double-ring flexural strength after sub-Tg post-annealing at various temperatures and times. The results demonstrate that sub-Tg post-annealing in two-step chemically strengthened peraluminous LAS glass is associated with a coupled evolution of residual stress relaxation and alkali-ion redistribution, rather than reconstruction of the aluminosilicate network. Raman spectroscopy shows that post-annealing below Tg does not induce significant changes in the average bonding configuration of the aluminosilicate network or in the stretching-dominated network connectivity, indicating that the silicate backbone remains essentially stable. Under this structural constraint, post-annealing promotes a coupled evolution of residual stress relaxation and alkali-ion redistribution. As the post-annealing temperature and time increase, K+ ions migrate inward from the near-surface region, whereas Na+ ions undergo bidirectional redistribution toward both the surface and the glass interior. This process involves reorganization of alkali charge-compensation environments around tetrahedral [AlO4]- units, together with a progressive redistribution of alkali ions within the near-surface compressive stress layer, and is associated with the opposite evolution of CS and DOL. Therefore, the compressive stress decreases while depth of layer increases, accompanied by a reduction in effective packing efficiency in the near-surface region. The reduced packing efficiency leads to gradual degradation of mechanical properties, manifested by decreases in flexural strength and Vickers hardness. These findings provide quantitative insight into the thermal stability of the compressive stress layer in chemically strengthened LAS glass and offer practical guidance for strength reliability after coating-related sub-Tg thermal cycles, such as those encountered during post-annealing of conductive ITO thin films.
Bioactive glasses (BGs) are widely investigated for biomedical applications due to their bioactivity, ion release capability, and potential antimicrobial behavior. In this work, a novel zinc/potassium-doped BG, designated as Gaia-GN, was synthesized using the melt-quench technique. The thermal behavior was characterized through differential thermal analysis (DTA), thermogravimetry (TG), and heating microscopy (HM), which revealed a glass transition temperature of 513 degrees C and a broad processing window suitable for viscous-flow sintering. Subsequently, Gaia-GN powders were thermally processed to obtain sintered specimens. XRD analysis showed that sintering at relatively low temperatures, namely 600 degrees C, produced a compact and predominantly amorphous structure, minimizing the formation of crystalline phases. In addition, mechanical properties were evaluated by Vickers micro-indentation, determining Vickers hardness, Young's modulus, and fracture toughness using four different theoretical models. The results suggest that the combined presence of Zn and K improves thermal stability and mechanical performance compared with conventional formulations such as 45S5 Bioglass and S53P4. Finally, antimicrobial assays were conducted, revealing a strong antimicrobial action of the glass against Gram-negative bacteria. Overall, these findings underscore the potential of the new K/Zn-doped BG not only for its antibacterial properties but also for applications requiring thermal processing, such as the fabrication of scaffolds or coatings on metallic substrates.
Lead-free bismuthate-based sealing glasses are of growing interest for environmentally sustainable electronic and packaging applications. In this work, lead-free Bi2O3-ZnO-B2O3 glasses were modified through two distinct substitution routes-BaO replacing B2O3 and SrO exchanging for BaO-to evaluate their suitability for glass-to-metal sealing. BaO-for-B2O3 substitution reduced glass transition temperature (330 -> 325 degrees C) and increased coefficient of thermal expansion (13.0 -> 14.1 ppm/K) due to network depolymerization, yielding a low sealing range of 505-550 degrees C, but decreasing nanohardness (4.9 -> 4.6 GPa) and elastic modulus (69 -> 63 GPa). SrO-for-BaO exchange maintained nearly constant density and mechanical properties, with only minor fluctuations in thermomechanical properties, while supporting a sealing window of 520-580 degrees C. Raman spectra confirmed increasing nonbridging oxygen formation in BaO-substituted glasses, whereas SrO exchange induced only subtle structural shifts. Both systems formed diffusion-bonded interfacial layers (<2 & micro;m) with 304 stainless steel and showed thermal expansion compatibility (mismatch <10%), validating hermetic sealing. These results establish BaO-for-B2O3 substitution as advantageous for low-temperature sealing and SrO-for-BaO exchange as beneficial for stabilizing thermomechanical properties, offering complementary design strategies for sustainable lead-free sealing glasses.
Modeling of glass transition temperature (T g), chemical durability, and crystallization was carried out using the glass structure gene modeling (GSgM) approach for phosphate-based glasses containing simulated high-level waste (HLW) enriched in MoO3, ZrO2, and RE2O3. In this approach, the structural groups of phosphate glasses were derived from deconvolution of FTIR spectra, and high-accuracy structure-property models for the target properties were developed using limited experimental data. The chemical durability model also revealed the difference in the leaching behavior of Li+ relative to Na+ and K+, as well as La3+ relative to Ce3+ and Nd3+. Results showed that these structure-property models are preferable for property predictions and reliable for fast screening of new glass compositions.
