Sodium Borosilicate Research Articles

Investigation of acid exposure duration on migration behavior of sodium borosilicate glass-ceramic coatings

This study investigates the migration behavior of Na2O-B2O3-SiO2 glass-ceramic coatings under different exposure durations. Sinter-crystallization at 830 °C for 4.5 min transforms the glass into a crystalline phase. Coatings were immersed in 3% acetic acid solutions for durations ranging from 15 to 960 min. Chemical migration was measured using ICP-MS analysis, while SEM and surface profilometry assessed surface morphology and roughness. Coatings remained compliant with ISO 4531:2022 food-contact standard, even after 960 min. Dissolution of alkaline network modifiers initially increased roughness, which then returned to the initial value. This research provides insights into the stability and applicability of glass-ceramic coatings for long-term use in food-contact surfaces, contributing to the field of surface coatings and food safety.

Mechanical properties and structural evolution of sodium borosilicate glasses during uniaxial tension: Molecular dynamics simulation and experiments

The mechanical properties and structural evolution of sodium borosilicate glasses under the uniaxial tensile process were investigated through molecular dynamics simulation. The simulated properties of sodium borosilicate glasses were in good agreement with the experimental values. [BO3] and Na+ compensated [BO4] groups were generated in the glass network in low boron content, while [BO3] appeared with increasing boron oxide. The structure descriptor, Fnet synthesized the structure and energy information of the glass network which was positively correlated with Young's modulus. The strength has been diminished due to the decreased degree of polymerization of the glass network and the migration of Na+ cations. Simultaneously, the elastic deformation of sodium borosilicate glass arose from the motion of Na+ cations and alterations in the Si-O-Si bond angle. Moreover, the plastic deformation of sodium borosilicate glasses was attributed to the transition from [BO4] to [BO3] and the higher mobility of [BO3] than [BO4] and [SiO4].

Improving the mechanical properties of a sodium borosilicate glass through spinodal decomposition

AbstractThe brittleness of oxide glasses remains a critical problem, limiting their suitability for high‐performance and safety‐critical applications. In this study, we attempt to address this by synthesizing nanostructures in sodium borosilicate glasses through phase separation. While most previous work on the mechanical properties of phase‐separated glasses has focused on phase separation through nucleation and growth, we here create interconnected structures through spinodal decomposition. Interestingly, this leads to improvements in Vickers hardness (from 5.8 to 6.2 GPa), crack initiation resistance (from 4.9 to 8.1 N), and fracture toughness (from 0.85 to 1.09 MPa⋅m1/2). We show that the interconnected glassy phases deflect the propagating cracks, causing the required energy for cracks to cross phase boundaries to increase when subjected to external stress. This study deepens the understanding of how to address the brittleness problem of oxide glasses and provides a promising way to design high‐performance glass materials.

Highlighting amorphous phase separation process on cooling borosilicate melts using impedance spectroscopy

Four samples of sodium borosilicate glasses of composition (100 - x)(SiO2 - B2O3) - xNa2O with x = 4, 7, 10 and 25 mol% were synthesized and studied in a wide temperature range (up to 1673 K) using impedance spectroscopy, from the molten to the solid states. During melt cooling of three compositions (x = 4, 7 and 10), a clear transition was observed on the conductivity behavior at a critical temperature (Tcrit ≈ 973 K), highlighting the onset of an amorphous phase separation, in agreement with both Differential Scanning Calorimetry thermograms and literature. The amorphous nature of the phase separated samples was verified by in situ X-Ray Diffraction measurements performed under the same thermal conditions. Furthermore, Scanning Electron Microscopy micrographs taken on these three samples at room temperature after the impedance measurement confirmed the presence of two different phases, whose size and morphology vary with composition. As expected, the x = 25 sample did not show phase separation and remained homogeneous down to room temperature.

Influence of sodium oxide substitution on structural and gamma-ray radiation shielding properties of sodium borosilicate glass

In this paper, borosilicate glasses with varying concentrations of sodium oxide were synthesized using the melt-quenching method. The amorphous nature of the glasses under investigation, with a composition of (20 + x)Na2O-(60-x)B2O3–20SiO2 (where x = 0, 3, 5, 7, 8, 10, 13, 15, 17, and 20 mol%), was confirmed through X-ray diffraction (XRD) analysis. Fourier-transform infrared (FT-IR) spectroscopy was employed to analyze the glasses and revealed an increase in the concentration of non-bridging oxygen atoms (NBO) with increasing amounts of Na2O. The N4 parameter, which represents the fraction of NBOs, was calculated and found to decrease from 74% to 52% as the concentration of Na2O increased. The density of the glasses increased from 2.391 g/cm3 to 2.744 g/cm3 when B2O3 was replaced with Na2O, while the molar volume decreased from 27.68 cm3/mol to 23.56 cm3/mol. Theoretically, theoretical calculations were performed using newly developed computer software called Phys-PSD to assess their shielding properties, including attenuation coefficients, half value layer, and buildup factors. The calculations were conducted in the energy range of 0.015–15 MeV. The results indicated that the synthesized glasses exhibited promising potential as radiation shields.

Effect of Fe2O3 on the structure and properties of Mo‐containing borosilicate glasses for nuclear waste immobilization

AbstractAs a fission product in high‐level radioactive nuclear waste, Mo has low solubility in borosilicate glass. Fe2O3 is not only a prevalent transition metal element but also a major corrosion product in high‐level radioactive nuclear waste. Against this backdrop, the effect of Fe2O3 content on the structure and chemical durability of typical molybdenum‐containing sodium borosilicate glasses for nuclear waste immobilization are studied. The results show that the samples containing more than 3.85 mol% Fe2O3, a completely homogenous amorphous glass sample is obtained. Moreover, the mechanism of the effect of Fe2O3 on the solubility of Mo is discussed in detail. In this work, a portion of Fe3+ is reduced to Fe2+ and enters into the glasses as a charge compensation ion as Fe2+O6. Concurrently, Fe3+ ions contribute to the formation of the glass networks as Fe3+O4. Iron incorporation can improve the chemical durability of the sample.

Leaching behavior of glasses of the Na2O-B2O3-SiO2-Cr2O3 system

Porous glass (PG) obtained by leaching of sodium borosilicate glass (NBS) is actively used in sorption and separation technologies. Modifying the NBS system with additives can drastically affect the resulting PG. Here, we report on the effect that Cr2O3 had on the leaching behavior of phase-separated glasses in the Na2O-B2O3-SiO2-Cr2O3 system in 3 M HCl solution. The structure of these glasses was investigated by means of XRPD, EPR, and SEM. All chromium ions exist in the Cr3+ state and are octahedrally coordinated. Most Cr2O3 crystallized as eskolaite in the silica-rich phase. The leaching process is limited by the interdiffusion in the leached porous layer. Cr2O3 did not get extracted from the glass into a leaching solution. PGs containing a significant amount of eskolaite were obtained. The component extraction rate for Cr-doped glasses was higher than for Fe-containing glasses with similar compositions, which was explained by the difference in their structural roles.

Influence of the composition and structure of sodium borosilicate glasses on the optical-color characteristics of chromium aventurine glass in the presence of cobalt (II) oxide

We investigated the influence of cobalt (II) oxide additive in the amount of 1–3 mol.% on the structure and optical-color characteristics of chromium-containing glass with the following composition (mol.%): 29.6 Na2O; 19.7 В2О3; 49.3 SiO2; and 1.5 Cr2O3. The dependence of the optical-color characteristics of the glasses under study on the thermal treatment of the glass melt at a temperature of 10500C for 20 minutes was established. The thermal treatment resulted in the volumetric crystallization with the subsequent development of the aventurine effect. According to X-ray phase analysis data, the decorative effect was caused by Cr2O3 crystals. By using IR spectroscopy and differential thermal analysis, the structure of the experimental glasses was studied, and the influence of thermal treatment of glass melts on the formation of the structure of glass-ceramic material was established. Aventurine glass of dark blue-green color was obtained with a color tone =490 nm, color purity P=11.35%, and lightness L=5.454 %. The nature of the influence of cobalt (II) oxide on the optical-color characteristics of chromium-containing aventurine glass based on the Na2O–В2О3–SiO2 system is of interest for further development of new compositions of decorative ceramic glazes and enamel coatings.

Computer modeling of temperature distribution in the course of sintering of glass microspheres

Composite materials obtained by sintering glass microspheres are considered the promising ones for the underwater technology. The high indicators of the hydrostatic strength combined with the heat and sound insulation properties are due to the microspheres maintaining their shapes as close to the spherical as possible. The computer model of the temperature distribution is developed based on the physical and chemical conceptions of the glass composites structure formation by sintering the glass microspheres of sodium borosilicate composition and processing the experimental results of the temperature measurements. The modeling methodology is based on the principles of decomposition of the task by the researcher and ranking the temperature and time parameters. The ratio of the hydrostatic strength to the density of the samples is taken as a functional criterion and the software application is written in the Python language. The experimental setup that is used for sintering the glass microspheres enables to study the temperature fields and thermal deformation processes in real-time conditions. The coefficients of thermal conductivity of sintering are determined by the regular mode method. The results obtained are aimed at solving one of the most important scientific and practical issues of developing technologies for manufacturing glass composites for strategic purpose.

Evaluation of GlassNet for physics‐informed machine learning of glass stability and glass‐forming ability

AbstractGlassy materials form the basis of many modern applications, including nuclear waste immobilization, touch‐screen displays, and optical fibers, and also hold great potential for future medical and environmental applications. However, their structural complexity and large composition space make design and optimization challenging for certain applications. Of particular importance for glass processing and design is an estimate of a given composition's glass‐forming ability (GFA). However, there remain many open questions regarding the underlying physical mechanisms of glass formation, especially in oxide glasses. It is apparent that a proxy for GFA would be highly useful in glass processing and design, but identifying such a surrogate property has proven itself to be difficult. While glass stability (GS) parameters have historically been used as a GFA surrogate, recent research has demonstrated that most of these parameters are not accurate predictors of the GFA of oxide glasses. Here, we explore the application of an open‐source pre‐trained neural network model, GlassNet, that can predict the characteristic temperatures necessary to compute GS with reasonable performance and assess the feasibility of using these physics‐informed machine learning (PIML)‐predicted GS parameters to estimate GFA. In doing so, we track the uncertainties at each step of the computation—from the original ML prediction errors to the compounding of errors during GS estimation, and finally to the final estimation of GFA. While GlassNet exhibits reasonable accuracy on all individual properties, we observe a large compounding of error in the combination of these individual predictions for the PIML prediction of GS, finding that random forest models offer similar accuracy to GlassNet. We also break down the performance of GlassNet on different glass families and find that the error in GS prediction is correlated with the error in crystallization peak temperature prediction. Lastly, we utilize this finding to assess the relationship between top‐performing GS parameters and GFA for two ternary glass systems: sodium borosilicate and sodium iron phosphate glasses. We conclude that to obtain true ML predictive capability of GFA, significantly more data needs to be collected.

An insight into the structure of nanocomposites in porous glasses and their interactions after contact with the environment

Porous sodium borosilicate (SBS) glasses were prepared by conventional charge melting technique and TGS nanocomposites were prepared by introducing TGS crystals from a saturated solution into a pores matrix. The aim of this paper is to clarify the structure and surface changes of the SBS porous glasses before and after introducing TGS crystals. Thermal and dielectric measurements revealed the presence of phase transitions in TGS nanocomposites and confirmed the influence of crystallite size on the phase transition temperature. Powder X-ray diffraction (PXRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) revealed the morphological changes of the sample surfaces upon immersion in a TGS saturated solution. Additionally, the atomic ratio of empty porous glasses and TGS-PG nanocomposites was obtained by the XPS analysis. The visible differences in surface properties between empty porous glasses and TGS nanocomposites have been observed and discussed.

STUDY OF HYDROGEN-HELIUM PERMEABILITY OF SILICATE MICROSPHERES AND SORBENT BASED ON THEM

The work is devoted to research on the applicability of the membrane-sorption method for the separation of hydrogen-helium mixtures. The sorption dependences of hydrogen and helium absorption were experimentally obtained for synthetic hollow microspheres made of sodium borosilicate glass of the MS-V-1L type, silica microspheres and granular sorbent based on MS-V-1L microspheres. A significant difference in the rates of sorption processes of hydrogen and helium for the sorbents under study was shown. Based on the gas diffusion model, the kinetic characteristics of absorption, permeability and selectivity coefficients, and dynamic characteristics of the processes of sorption of hydrogen and helium of heliumhydrogen mixtures of various compositions by these sorbents were determined. For silica microspheres, the selectivity coefficient with respect to hydrogen and helium at T = 24 C exceeds 130, and for a granular sorbent based on MS-V-1L microspheres it is about 1000 at T =110 C. The high selectivity values of the studied sorbents confirm the possibility and efficiency of using the membrane-sorption method for the separation of hydrogen-helium mixtures.

The effect of NaF and ZnO on regulating the network topological structure of CsPbBr3 quantum dots-embedded sodium borosilicate glass for energy-efficient dust indicator

All-inorganic CsPbX3 (X = Cl, Br, I) perovskite quantum dots (QDs) exhibit substantial potential in optoelectronics, rendering them valuable materials for next-generation lighting. However, the high cost and substantial usage of Cs present challenges. This study investigates the impact of NaF and/or ZnO modifiers on the network topological structure of CsPbBr3 QDs-embedded sodium borosilicate (SBS) glass. The incorporation of NaF and ZnO not only reduces Cs consumption and energy requirements during heat treatment but also enhances the stability and optical properties of CsPbBr3 QDs. Through a combination of experimental analysis and molecular dynamics (MD) simulations, we explore the changes in the SBS glass network topology induced by these modifiers. The results demonstrate that the addition of these modifiers effectively alters the topological structure of SBS glass, providing outstanding water and heat resistance for the embedded CsPbBr3 QDs. This suggests that the NaF and ZnO co-modified CsPbBr3 QDs-embedded SBS glass, with improved stability and optical characteristics, exhibits great promise for applications in optoelectronics.

The dry-gel conversion synthesis of the lithium sodium borosilicate jadarite, LiNaSiB3O7(OH)

Abstract The lithium sodium borosilicate jadarite, LiNaSiB3O7(OH), was first identified in 2007 in the Jadar basin, Serbia, where it forms the principal ore mineral of one of Europe's largest Li deposits. We report the successful application of the dry-gel conversion technique (DGC) to synthesise a jadarite analogue, via a dry-gel precursor made using sol-gel synthesis and the inclusion of the structure directing agent tetraethylammonium hydroxide (TEAOH). Pawley refinement of powder X-ray diffraction (PXRD) data collected on the synthetic sample was carried out using a monoclinic unit cell in space group P21/c (Whitfield et al., 2007), and gave refined unit cell parameters of a = 6.824(3) Å, b = 13.882(5) Å, c = 7.735(3) Å and β = 124.37(1)° (Rwp = 9.22). Inductively-coupled plasma optical emission spectroscopy (ICP–OES) on the synthetic sample confirmed an empirical formula of Li1.07Na1.40Si0.79B3O7.32(OH), based on three B atoms per formula unit (apfu). The synthetic product was found to be deficient in Si compared to natural jadarite from analysis of PXRD and ICP–OES data. Fourier-transform infrared spectroscopy (FTIR) showed that synthetic jadarite has peaks at 1415 and 1342 cm–1 and between 1180 and 900 cm–1, which are attributed to the presence of trigonal (BO3) and tetrahedral (BO4) borate groups characteristic of the natural jadarite structure, as well as a broad peak at 3441 cm–1 due to the presence of residual TEAOH. Scanning electron microscopy showed similarities in the morphologies between synthetic and natural jadarite particles.

Effect of compression temperature on the structure and properties of hot compressed sodium borosilicate glasses from molecular dynamics simulations

Applying pressure during glass formation or annealing is an effective method to modify the properties of oxide glasses. The effect of compression temperature on the structure and properties of a sodium borosilicate glass has been investigated using molecular dynamics simulations. The connection between macroscopic properties (density and elastic moduli) and microscopic structures (short- and medium-range order) was investigated. Young’s modulus increased with the compression temperature and then reached a plateau at temperatures close to the glass transition temperature. The modulus increase was found to correlate linearly with glass density change. Correlations with structural changes, such as fraction of four-fold coordinated boron, oxygen triclusters, sodium ion coordination number and the Na–O and Na–Na distances were studied. The results suggest that the pressure-induced transformation from three-fold to four-fold coordinated boron was achieved through the formation of oxygen triclusters, which is different from the commonly observed mechanism involving nonbridging oxygen during the boron coordination change. In addition, the linear correlation between sodium coordination number and glass density suggests that change of sodium ion local environment and redistribution of sodium ions also play an important role in the property behaviour during pressure quenching of the glasses.

CFD Modeling and Analysis of a Heat-Generating Melt Pool Under External Vessel Cooling and Top Flooding

In some nuclear reactors, under accidental conditions, core debris forms a molten pool, which is later located in a core catcher. The core catcher proposed by the authors uses special refractory material to absorb enthalpy of corium so that temperatures are within 1500 K, which is possible to cool with side cooling and top flooding. Since performing a full-scale prototypic experiment is extremely challenging and complex because of the involvement of very high temperatures and the presence of radioactive materials, it is important to develop a Computational Fluid Dynamics (CFD) model capable of simulating coolability of the melt pool with the above cooling strategy. In the present work, a CFD model was developed for the above purpose and was benchmarked with experiments conducted under simulated conditions by the authors. The experiment involved the melting of about 25 L of sodium borosilicate glass at about 1473 K and cooling it in a scaled-down core catcher model. In the presence of decay heat inside the melt pool, turbulent natural convection plays an important role in the temperature distribution inside the melt pool and on the vessel walls. For this, we used different turbulence models. Comparisons among the Standard k-ε, Shear Stress Transport (SST) k-ω, and two-dimensional (2D) Large Eddy Simulation (LES) turbulence models show that SST k-ω and 2D LES turbulences are found to be in good agreement with the experimental results for the temperature distribution in the melt pool, and SST k-ω is found to be computationally less expensive than 2D LES. In general, the CFD model is capable of simulating heat transfer with phase changes inside the heat-generating melt pool. In view of this, the model can be further extended to include cooling of the melt pool in the prototype core catcher. The evolution of crust formation has been investigated in detail using a CFD model.

Predicting the pair correlation functions of silicate and borosilicate glasses using machine learning.

Glasses offer a broad range of tunable thermophysical properties that are linked to their compositions. However, it is challenging to establish a universal composition-property relationship of glasses due to their enormous compositions and chemical space. Here, we address this problem and develop a metamodel of the composition-atomistic structure relationship of a class of glassy materials via a machine learning (ML) approach. Within this ML framework, an unsupervised deep learning technique, viz., a convolutional neural network (CNN) autoencoder, and a regression algorithm, viz. random forest (RF), are integrated into a fully automated pipeline to predict the spatial distribution of atoms in a glass. The RF regression model predicts the pair correlation function of a glass in a latent space. Subsequently, the decoder of the CNN converts the latent space representation to the actual pair correlation function of the given glass. The atomistic structures of silicate (SiO2) and sodium borosilicate (NBS) based glasses with varying compositions and dopants are collected from molecular dynamics (MD) simulations to establish and validate this ML pipeline. The model is found to predict the atom pair correlation functions for many unknown glasses very accurately. This method is very generic and can accelerate the design, discovery, and fundamental understanding of the composition-atomistic structure relationship of glasses and other materials.

Classical molecular dynamics simulations of CsPbBr3 perovskite quantum dots embedded sodium borosilicate glasses

We have simulated the configuration of perovskite CsPbBr3 quantum dot (QD), sodium borosilicate (SBS) glass matrix, and the combination of these two, namely CsPbBr3 QDs embedded SBS glass. We delineate a microscope porthole containing ∼100,000 atoms and with a dimension of ∼30 nm × 30 nm × 1 nm, using the classical molecular dynamics (CMD) benefiting from graphics processing unit (GPU) acceleration. We quantify the structural properties of glass matrix and determined the crystallization of QDs, in excellent agreement with experimental observations. Based on analysis the of boron coordination, structural undulation influenced by the K value (KSiO2/B2O3), we demonstrate the significant compositional repulsion in the combination derived from electronegative nonmetal elements, namely oxygen (O) and bromine (Br). As the K value decreases, indicating an increase in the proportion of B2O3 and a decrease in the proportion of SiO2, the [BO3]/[BO4] ratio increases, resulting in a glass matrix with a stronger repulsive 'anionic sea' and a more relaxed encapsulated environment for CsPbBr3 QD. This creates greater repulsion for the allocation of oxide and bromide, and a more suitable space for the crystallization of CsPbBr3 clusters, which in turn regulates the formation of CsPbBr3 QDs. These results constructively extend our understanding of the microstructure of CsPbBr3 QDs embedded SBS glasses, and provide valuable insights for the engineering of CsPbBr3 QDs in SBS glasses on high luminescent CsPbBr3 QDs embedded glasses.

Effect of P2O5 on the structure and phase separation of sodium borosilicate glasses

Effect of P2O5 on the structure and phase separation of sodium borosilicate glasses

Effects of Fe2O3-[BOx] reaction on sodium borosilicate glass structure doping with nano to macro sized α-Fe2O3 particles

Fe3+ is readily reacted with structural units to modify various properties of the borosilicate glasses and glass ceramics. However, there exists some controversies on Fe2O3 containing borosilicate glasses: (1) whether the Fe2O3 turned into the nanometer-sized polycrystalline structure or reacted with the glass matrix to form a new substance and (2) whether the role of Fe2O3 was depended on its concentration in the network of glass. Theoretical extinction spectra of α-Fe2O3 particles ranging from 1 to 180 nm in borosilicate glass align with UV–vis absorption spectra. Based on the Na2O-B2O3-Fe2O3 phase diagram, xFe2O3·(100-x) [41.6B2O3–20.7Na2O-19.2CaO-9.7Al2O3–7.0SiO2–0.6ZnO] (x=1.20∼1.95 mol%) were prepared for this study, analyzing from exterior characteristics to interior structure. Molecular vibrational spectroscopy and component structure measurement were applied to study the effect of doping α-Fe2O3 powders (particle sizes of 30 nm, 1 μm, 75 μm) on the sodium borosilicate glasses. Combination of experimental characterization and numerical simulation were also utilized to investigate the effects of iron oxide particle size on the color of dispersion systems. We discovered that (i) doping with either nanometer-sized or micron-sized particles of α-Fe2O3 can result in both the substitution for B3+ in tetra-coordination [BO4] and the bonding with [BO3] units within the amorphous network of sodium borosilicate glasses; (ii) Even at lower concentrations, α-Fe2O3 can still act as a network intermediate, combining both its former role and modifying properties. Based on these outcomes, for the reactive process, we formulated a constitutive model which offers valuable insights into understanding the behavior of iron oxide in sodium borosilicate glass. These findings are crucial for comprehending the processes involved in matrix preparation and are pivotal for progressing to the subsequent stage where designing and fabricating nanocomposite materials based on these matrices with spatial separation.