Sodium Borosilicate Glass Research Articles

Reevaluating the efficacy of moderate annealing in nuclear waste vitrification for sustainable high-level waste management

The reliable immobilization of nuclear waste, particularly high-level waste (HLW), is a key issue for sustainable utilization of nuclear energy. Annealing process is adopted in nuclear waste vitrification to improve mechanical properties of products; however, its efficacy on chemical stability of treated HLW glass remain uncertain. This study aims to reevaluate the effects of moderate annealing on chemical durability of sodium borosilicate glass matrix incorporated with simulated HLW. Two types of leaching tests, i.e. acid leaching and the modified Product Consistency Test (PCT), were performed to examine the leaching behavior of HLW glassy products controlled by corrosion mechanisms of ion exchange and hydrolysis, respectively. The acid leaching results showed that annealed glass samples released lanthanum (La) species at a faster rate than that of quenched samples, but the effects of annealing on the release behavior of alkaline and alkaline-earth elements were limited. In contrast, the PCT results showed minor difference between quenched and annealed samples, which suggests that the small structure modification caused by moderate annealing was not comparable with the dominant hydrolysis reaction occurred in the PCT process. According to the free-volume theory, as well as evidences derived from Raman characterization and thermodynamic measurements, La was inferred to exist in the free-volume region in the HLW glass, and the annihilation of free volume during annealing could mobilize La from its stable surrounding environment, and thus reducing the chemical stability of nuclear waste glass.

Adsorption of Iron(III) Ions on Porous Glass with Different Pore Space Structures

The article studies the adsorption of iron ions from solutions of iron(III) chloride with a concentration of 10–4–10–3 M at pH 3 on micro- and macroporous glass, as well as on microporous glass heat-treated at 750°C, obtained from two-phase sodium borosilicate glass. It is found that the adsorption values at a constant concentration of the iron chloride solution are a function of the structural parameters of the porous glass (PG). It is shown that the Freindlich and Langmuir adsorption isotherms can be used to analyze the experimental data and the constants of these isotherms are found. In the systems studied, adsorption mainly occurs via the monolayer mechanism.

Calcium nitrate: A chemical admixture to inhibit aggregate dissolution and mitigate expansion caused by alkali-silica reaction

Alkali-silica reaction (ASR) is a significant cause of the degradation of concrete structures. ASR results from the dissolution of reactive silicate aggregates and the subsequent formation of damaging, expansive ASR gels. Despite the prevalence of ASR, so far only lithium-based chemical admixtures have been shown to be successful in mitigating its deleterious effects. Herein, dissolved calcium nitrate (Ca(NO3)2: CN) is demonstrated to reduce ASR-induced expansion caused by the use of sodium borosilicate (NBS) glass as a model reactive aggregate. The significance of reductions of NBS-glass dissolution and mortar-bar expansion rates is discussed, with special focus on highlighting the mechanism by which calcium nitrate mitigates ASR, i.e., by the inhibition of aggregate dissolution. This study reveals a new and cost-effective pathway to suppress aggregate dissolution and ASR in concrete based on the dosage of soluble alkaline-earth additives.

Effect of copper addition on stability of bioceramics based on biogenic hydroxyapatite and sodium borosilicate glass in physiological solutions

Effect of copper addition on stability of bioceramics based on biogenic hydroxyapatite and sodium borosilicate glass in physiological solutions

Thermal properties of sodium borosilicate glasses as a function of sulfur content

AbstractSulfur trioxide (SO3) additions, up to 3.0 mass%, were systematically investigated for effects on the physical properties of sodium borosilicate glass melted in air, with a sulfur‐free composition of 50SiO2–10Al2O3–12B2O3–21Na2O–7CaO (mass%). Solubility measurements, using electron microscopy chemical analysis, determined the maximum loading to be ~1.2 mass% SO3. It was found that measured sulfur (here as sulfate) additions up to 1.18 mass% increased the glass transition temperature by 3%, thermal diffusivity by 11%, heat capacity by 10%, and thermal conductivity by 20%, and decreased the mass density by 1%. Structural analysis, performed with Raman spectroscopy, indicated that the borosilicate network polymerized with sulfur additions up to 3.0 mass%, presumably due to Na2O being required to charge compensate the ionic additions, thus becoming unavailable to form non‐bridging oxygen in the silicate network. It is postulated that this increased cross‐linking of the borosilicate backbone led to a structure with higher dimensionality and average bond energy. This increased the mean free paths and vibration frequency of the phonons, which resulted in the observed increase in thermal properties.

A Glass Platelet Coating on Battery Electrodes and Its Use as a Separator for Lithium-Ion Batteries

Abstract A new type of separator for lithium-ion batteries (LIBs) has been developed using ultrathin micrometer-sized sodium borosilicate glass platelets coated directly on a battery electrode with a water-based binder. The coating process is described in detail, demonstrating coating thicknesses of the glass separator of less than 50 µm. The high-temperature stability has been investigated and it has been shown that the separator is dimensionally stable to at least 600 °C. With regard to the electrochemical performance, full-cell tests on graphite || lithium iron phosphate cells showed a very good behavior, according to which comparable properties of the electrode/separator compound to a commercial polymer-based separator were achieved. This glass separator/electrode composite shows an interesting property profile and is a temperature-stable alternative to conventional polymer-based separators.

An insight into inorganic glasses and functional porous glass-based nanocomposites

Properties of dielectric and magnetic porous matrices and ferroelectrics porous glasses based nanocomposites were studied. Two types of modified and unmodified by iron oxides initial sodium borosilicate glasses and obtained from them porous matrices were investigated. The continuous pore structure was observed in porous glasses and additional in iron containing porous glasses inclusions of iron phase were stated. Depending on technological processes the pore diameters were estimated to be between 4 and 60 nm. The effect of structure and composition of investigated materials on electrical properties was discussed. Dynamic Impedance Spectroscopy measurements have revealed reversible. The dc conductivity and relaxation processes related to different types of transport of sodium and iron ions were discussed. The existence of ferroic KNO3 inside pores determines properties of nanocomposite based on porous matrices. The obtained porous dielectric and magnetic matrices can be applied as ferroics and multiferroeics elements.

Effect of the iron content on the structure and electrical properties of sodium borosilicate glasses: XRD, TEM, Mössbauer, FTIR and DIS spectroscopy study

The iron-bearing sodium borosilicate glasses with different contents of iron were prepared by the charge melting method and studied by XRD, TEM, FTIR, Mössbauer and Dynamic Impedance Spectroscopy techniques. An analysis and the transmittance spectra of two-phase sodium borosilicate glasses with different contents of iron oxide were carried out. A usage of the Mössbauer spectroscopy revealed differences between two-phase and porous glasses. In both cases Fe2+ and Fe3+ ions in octahedral and tetrahedral coordination were found, while in the two-phase glasses the significant contribution of magnetite was additionally detected. The activation energy associated with the relaxation processes determined from the electric modulus spectra was found to be in a range between 0.986 eV and 0.729 eV, which is close to the activation energy for dc conductivity. Two different conduction mechanisms were observed and their physical origin was explained. The hopping between two valence states of iron and the sodium ion conduction mechanism was additionally discussed.

Investigation of Hydrolytic Polycondensation in Systems Based on Tetraethoxysilane by DK-Spectrophotometry Method

The research of the hydrolytic polycondensation kinetics of tetraethoxysilane (TEOS) is required in order to understand the sol-gel synthesis processes and identify the factors determining the direction of these processes. An extensive analysis of these problems permits us to predict appropriate ways for the synthesis of new substances with the predetermined properties. Studying the kinetics of the polycondensation of TEOS above the gel point will allow solving problems of the gels’ strength and the gels’ degree of structuring and thus optimizing the conditions of the further processing materials for the production of the final synthesis products. In this paper the results of the research on the structuring kinetics of the silica in the modeled aqueous-alcoholic solutions of TEOS, including boron-containing solutions, before and after the gel point at various molar ratios of H2O : SiO2 and pH values of 2.0 and 6.0 by the differential kinetic spectrophotometry are presented. The kinetic scheme developed by the authors and the mathematical tool allow determining the degree of the direction of the process of silica polycondensation. The data obtained on the model systems were applied to the description of the silica structuring process in the acid solutions resulting from the treatment of the single-phased sodium borosilicate glass. The obtained results will form the base for the interpretation of the experimental data on the kinetics of the silica structuring contained in the unstable phase of the two-phased alkali-borosilicate glass during the leaching process; i.e., it will allow predicting the dissolution rate, forms of existance, gelation time, strata formation time and, as a consequence, the formation of some porous structure of the resulting porous glass.

Production and properties of phase separated porous glass

A sodium borosilicate glass (SBG) was produced by conventional melt-quenching. As cast glass was heat treated to induce phase separation (SBG-HT), followed by acid leaching with HCl to dissolve one of the separated phases; i.e. alkali rich borate phase, so that a porous glass (PG) was obtained. In order to alter the pore structure, produced PG was subsequently alkali (NaOH) leached or alternatively heat treated. The samples were characterized by techniques including XRD, SEM, N2 adsorption/desorption. The total pore volume for PG was found to be 0.314 cm3/g, reached to 0.370 cm3/g by alkali leaching, instead decreased to 0.227 cm3/g by heat treatment. The microhardness and tribological properties of SBG-HT and all PGs were evaluated by Vickers hardness and by pin on disk tribometer. For all PGs the microhardness values were lower, instead the wear rates were higher than that of the parent SBG-HT.

Hydroxyl-Group Identification Using O K-Edge XAFS in Porous Glass Fabricated by Hydrothermal Reaction and Low-Temperature Foaming.

Porous glass was prepared by the hydrothermal reaction of sodium borosilicate glass, and oxygen-ion characterization was used to identify the hydroxyl groups in its surface area. A substantial amount of “water” was introduced into the ionic structure as either OH− groups or H2O molecules through the hydrothermal reaction. When the hydrothermally treated glass was reheated at normal pressures, a porous structure was formed due to the low-temperature foaming resulting from the evaporation of H2O molecules and softening of the glass. Although it was expected that the OH− groups would remain in the porous glass, their distribution required clarification. Oxygen K-edge X-ray absorption fine structure (XAFS) spectroscopy enables the bonding states of oxygen ions in the surface area and interior to be characterized using the electron yield (EY) and fluorescence yield (FY) mode, respectively. The presence of OH− groups was detected in the O K-edge XAFS spectrum of the porous glass prepared by hydrothermal reaction with a corresponding pre-edge peak energy of 533.1 eV. In addition, comparison of the XAFS spectra obtained in the EY and FY modes revealed that the OH− groups were mainly distributed in the surface area (depths of several tens of nanometers).

CdS/TiO2 heterojunction in glass matrix: Synthesis, characterization, and application as an improved photocatalyst

In this paper, sodium borosilicate glass SiO2-B2O3-Na2O-ZnO with 2 wt% CdS and 1 wt% TiO2 were prepared by the melt quench technique. For the growth of QDs, single-step heat treatment was given using glass transition (Tg) and glass crystallization (Tc) temperature. Hexagonal and anatase phase of grown CdS and TiO2 QDs were confirmed by XRD pattern. The size of powders was observed by SEM and cluster formation of CdS/TiO2 QDs was studied by FESEM. EDS pattern confirms the elemental composition which was used during synthesis. The structural changes due to heat treatment were explored by FTIR study. The growth of QDs and size determination was done by HRTEM. An increase in the size of QDs with annealing time was confirmed by optical absorption and emission spectra.Photocatalytic activity of Cd3:3 h (5.33 μm) and Cd3:5 h (3 μm) is investigated by degrading indigo carmine (IC) dye and degradation efficiency was found to be 85.30% and 91.64% respectively for 5 h.

Monte Carlo simulation of borosilicate glass dissolution using molecular dynamics-generated glass structures

Atomic-scale insights into borosilicate glass dissolution are critical to the development of waste form corrosion models. While Monte Carlo (MC) simulations have been instrumental in advancing the state of knowledge, all simulations to date have relied on lattices to represent the glass structure, potentially introducing artifacts. A new approach (amorphous MC approach) was developed whereby glass structures generated from molecular dynamics simulations were used as starting points for MC simulations. Correlations between dissolution rate and structural features were revealed in MC simulations of sodium borosilicate glasses that covered a wide compositional range. Notably, the lattice MC approach predicted the fraction of tetrahedral boron to have a lesser influence on the dissolution rate than computed with the amorphous MC approach. The lattice MC simulations also overestimated the dissolution rate for a given glass composition. These findings highlight the importance of using truly amorphous structures in MC simulations of glass corrosion.

Predicting Composition-Structure Relations in Alkali Borosilicate Glasses Using Statistical Mechanics

Predicting the atomic-scale structure of multicomponent glasses from their composition and thermal history would greatly accelerate the discovery of new engineering and functional glasses. A statistical mechanics-based approach has recently been applied to predict the composition-structure evolution in binary oxide glasses by determining the relative entropic and enthalpic contributions to the bonding preferences. In this work, we first establish the network modifier-former interaction parameters in sodium silicate and sodium borate glasses to predict the structural evolution in sodium borosilicate glasses. Due to the significant fluctuations in the experimentally determined structural speciation in borosilicate glasses, we perform classical molecular dynamics (MD) simulations to establish and validate our structural model. We also show that the statistical mechanical model naturally accounts for the difference in structural speciation from MD simulations and NMR experiments, which in turn arises from the difference in cooling rate and thus thermal history of the glasses. Finally, we demonstrate the predictive capability of the model by accurately accounting for the structural evolution in potassium borosilicate glasses without using any adjustable model parameters. This is possible because all the interaction parameters are already established in the potassium silicate, potassium borate, and sodium borosilicate glasses, respectively.

Sodium borosilicate glass doped with Ni nanoparticles: Structure, formation mechanism and nonlinear optical properties

Sodium borosilicate(Na2O-B2O3-SiO2, NBS) glass doped with Ni nanoparticles has been successfully prepared by a sol-gel technique combined with atmosphere control method. Thermal gravimetric (TG) and Fourier transform infrared (FTIR) are used to study the feasibility formation mechanism from the xerogel to densified NBS glass network. X-ray powder diffraction (XRD), transmission electron microscopy (TEM) as well as X-ray photoelectron spectra (XPS) analysis reveal that the cubic structure of metal Ni with uniform spherical shape has formed in the NBS glass matrix. The average size is determined to be 11.85 nm. In particular, a mechanism for the formation of Ni/NBS glass is proposed based on the microstructure, BET analysis and N2 adsorption aperture curve. At last, nonlinear optical properties of Ni/NBS glass are investigated by using the Z-scan technique with a Ti:Sapphire laser at 800 nm. Results illustrate that the third-order optical nonlinear susceptibility χ(3) of the glass reaches to 5.51 × 10−12 esu.

Laser Writing of Polarization-Sensitive Birefringence in Sodium-Borosilicate Glass

It is demonstrated that femtosecond laser pulses can be used to form birefringent microregions in sodium borosilicate glass with the composition 68 SiO2, 27 B2O3, 4 Na2O, and 1 Al2O3 (mol.%); the birefringence is associated with the formation of nanogratings and its slow axis is oriented perpendicular to the polarization plane of the writing laser beam. The dependences of the phase shift of the light passing through these microregions on the number and energy of the laser pulses forming them are determined. It is shown by means of confocal RS spectroscopy that the content of sodium cations decreases in the formed microregions.

Leaching studies on borosilicate glasses for the immobilization of high-level radioactive waste in the pellet form subjected to aggressive test conditions

Pellet leaching and associated thermal and structural changes of sodium borosilicate (NBS) glass, used for the immobilization of high-level radioactive liquid waste, subjected to aggressive test conditions have been compared with international simple glass (ISG) subjected to the same leaching conditions. The crystalline phase getting separated out from NBS glass is found to be different for pellets and powder leaching experiments and this has been explained based on the difference in the extent of leaching occurring with glass samples in the two experiments. Based on Fourier transform infrared studies, it is inferred that, unlike in the ISG sample, Si–O–Si/B structural units become more ordered with the leaching in the case of NBS glass, and this is attributed to the partial network destruction occurring with NBS glass and crystallization of the \(\hbox {SiO}_{2}\) phase from the glass matrix. Both the NBS glass and ISG sample show L-centre emission and the emission intensity remained unaffected with leaching, confirming that the local environment around non-bridging oxygen atoms in the NBS glass and ISG sample are unaffected and leaching occurs through network dissolution.

Assessment of interatomic parameters for the reproduction of borosilicate glass structures via DFT‐GIPAW calculations

AbstractBorates and borosilicates are potential candidates for the design and development of glass formulations with important industrial and technological applications. A major challenge that retards the pace of development of borate/borosilicate based glasses using predictive modeling is the lack of reliable computational models to predict the structure‐property relationships in these glasses over a wide compositional space. A major hindrance in this pursuit has been the complexity of boron‐oxygen bonding due to which it has been difficult to develop adequate B–O interatomic potentials. In this article, we have evaluated the performance of three B–O interatomic potential models recently developed by Bauchy et al [J. Non‐Cryst. Solids, 2018, 498, 294–304], Du et al [J. Am. Ceram. Soc. https://doi.org/10.1111/jace.16082] and Edèn et al [Phys. Chem. Chem. Phys., 2018, 20, 8192–8209] aiming to reproduce the short‐to‐medium range structures of sodium borosilicate glasses in the system 25 Na2O x B2O3 (75 − x) SiO2 (x = 0‐75 mol%). To evaluate the different force fields, we have computed at the density functional theory level the NMR parameters of 11B, 23Na, and 29Si of the models generated with the three potentials and the simulated MAS NMR spectra compared with the experimental counterparts. It was observed that the rigid ionic models proposed by Bauchy and Du can both reliably reproduce the partitioning between BO3 and BO4 species of the investigated glasses, along with the local environment around sodium in the glass structure. However, they do not accurately reproduce the second coordination sphere of silicon ions and the Si–O–T (T = Si, B) and B‐O‐T distribution angles in the investigated compositional space which strongly affect the NMR parameters and final spectral shape. On the other hand, the core‐shell parameterization model proposed by Edén underestimates the fraction of BO4 species of the glass with composition 25Na2O 18.4B2O3 56.6SiO2 but can accurately reproduce the shape of the 11B and 29Si MAS‐NMR spectra of the glasses investigations due to the narrower B–O–T and Si‐O‐T bond angle distributions. Finally, the effect of the number of boron atoms (also distinguishing the BO3 and BO4 units) in the second coordination sphere of the network former cations on the NMR parameters have been evaluated.

Effects of energy deposition on mechanical properties of sodium borosilicate glass irradiated by three heavy ions: P, Kr, and Xe

Sodium borosilicate glasses are candidate materials for high-level radioactive waste vitrification; therefore, understanding the irradiation effects in model borosilicate glass is crucial. Effects of electronic energy deposition and nuclear energy deposition induced by the impact of heavy ions on the hardness and Young’s modulus of sodium borosilicate glass were investigated. The work concentrates on sodium borosilicate glasses, henceforth termed NBS1 (60.0% SiO2, 15.0% B2O3, and 25.0% Na2O in mol%). The NBS1 glasses were irradiated by P, Kr, and Xe ions with 0.3 MeV, 4 MeV, and 5 MeV, respectively. The hardness and Young’s modulus of ion-irradiated NBS1 glasses were measured by nanoindentation tests. The relationships between the evolution of the hardness, the change in the Young’s modulus of the NBS1 glasses, and the energy deposition were investigated. With the increase in the nuclear energy deposition, both the hardness and Young’s modulus of NBS1 glasses dropped exponentially and then saturated. Regardless of the ion species, the nuclear energy depositions required for the saturation of hardness and Young’s modulus were apparent at approximately 1.2 × 1020 keV/cm3 and 1.8 × 1020 keV/cm3, respectively. The dose dependency of the hardness and Young’s modulus of NBS1 glasses was consistent with previous studies by Peuget et al. Moreover, the electronic energy loss is less than 4 keV/nm, and the electronic energy deposition is less than 3.0 × 1022 keV/cm3 in this work. Therefore, the evolution of hardness and Young’s modulus could have been primarily induced by nuclear energy deposition.

Monte Carlo simulation of the corrosion of irradiated simplified nuclear waste glasses

Ballistic effects due to recoil nuclei will be the predominant mode of long-term radiation damage of nuclear waste glass in disposal facilities. While these ballistic effects are known to modify the glass structure in ways that have been quantified using molecular dynamics (MD) simulations, the effect of irradiation-induced structural changes on glass corrosion is not understood. Monte Carlo (MC) simulations were therefore performed to quantify the effects of structural changes determined from MD simulations on the corrosion of simplified nuclear waste glasses, namely sodium borosilicate and sodium alumino-borosilicate glasses. MC simulations were first performed to determine separately the effects of irradiation-induced changes in boron coordination, the number and nature of Qn species, and the angular distribution of SiOSi linkages, that is, changes to the short-range order of the glass. Generally, the MC simulations showed the resulting effects on the kinetics (B release rate) and extent (B leached thickness) of corrosion were correlated to the extent of depolymerization of the glass network introduced by these local structural changes. The combined effects of these structural changes, as parameterized using the results of MD simulations, were then determined using a glass composition for which relevant experimental data were available for comparison. Here, the combined effect of local changes was lower than the increase in alteration depth observed upon irradiation. This insight from the MC simulations highlighted the need to consider changes in the medium-range order to completely account for experimental observations.