Alkali Borosilicate Glasses Research Articles

Structural Aspects of Ambient-Temperature Densification of Highly Crack-Resistant Borosilicate and Aluminoborosilicate Glasses: Two Case Studies Examined by Solid-State NMR.

The structural aspects of ambient-temperature densification via pressurization at 25 GPa were studied by solid-state NMR for two case studies: An alkaline earth boroaluminosilicate glass with the composition 6CaO-3SrO-1BaO-10Al2O3-10B2O3-70SiO2 (labeled SAB) and a sodium magnesium borosilicate glass with the composition 10Na2O-10MgO-20B2O3-60SiO2 (labeled MNBS). For SAB glass, cold pressurization results in significant increases in the average coordination numbers of both boron and aluminum, in line with previous results found in hot-compressed alkali aluminoborosilicate glasses. In addition, 27Al/11B dipolar recoupling experiments reveal a significant decrease in the 11B/27Al dipolar interaction strength upon pressurization, suggesting that the higher-coordinated boron and aluminum species experience weaker magnetic interactions. While this is an expected consequence of the longer internuclear distances involving higher coordination states, the magnitude of the effect also is consistent with a decrease of average B-O-Al internuclear connectivity. By conjecture, a decreased B-O-Al connectivity may present a mechanism of plastic flow inhibiting crack initiation in aluminoborosilicate glasses. In the case of the MNBS glass, no change in the average boron coordination number was observed within experimental error; however, densification increases the extent of B-O-Si connectivity at the expense of small ring structures with dominant B-O-B connectivity. With regard to boron coordination, the data obtained for both case studies differ from those previously found in a series of alkali borosilicate glasses, which had shown an unexpected decrease in N4 upon increased pressure. The results of the present study highlight the importance of changes of medium-range order regarding densification.

Nanoporous glass as prospective material for fiber optics

The method of manufacturing active silica fibers by sintering nanoporous glasses has a number of advantages over methods of vapor deposition (MCVD, OVD). The features of obtaining nanoporous glasses by the method of two-phase separation of alkali borosilicate glasses are described. Examples of doping sintered nanoporous glasses with rare earth elements are given and the main results on the production of active fibers with a core are considered. It has been shown that such fibers are similar to their MCVD analogues in terms of properties. At the same time, it is possible to impregnate nanoporous glass with large (more than 1 at.%) concentration of dopants without revealing clustering effects and without noticeable fluctuations in the refractive index of the fiber core glass.

Statistical model of synchronized cooperative motion in glass-forming liquids

This paper presents a theoretical framework describing the tendency for synchronized positional rearrangements of any two structural species in a multicomponent glass-forming liquid. Such correlated motions are especially important as the glass-forming liquid approaches the glass transition. It is established that the expected cage-breaking probability of a structural unit is proportional to the dynamical propensity of the structural unit calculated via the isoconfigurational ensemble method. This theoretical framework supports the notion that spatial heterogeneities in composition result in dynamical heterogeneities, enabled by synchronized positional rearrangements. Using this model, an alkali borosilicate glass is investigated as an example, and results indicate that structural species with large differences in enthalpy might inhibit the expansion of cooperative rearranging regions and increase the number of such regions. The physical impact on relaxation time distribution and configurational entropy are also discussed.

Densification of Sodium Borosilicate Glasses at Ambient Temperature: Structural Investigations by Solid-State Nuclear Magnetic Resonance and Raman Scattering

Alkali-borosilicate glasses with composition (80-x)SiO2-xB2O3-20Na2O (10 ≤ x ≤ 30) were subjected to a 25 GPa compression and decompression at room temperature, resulting in density increases between 1.4% and 1.9%. The structural changes associated with this process have been investigated and compared with uncompressed glasses having the same thermal history. Systematic trends are identified, using Raman scattering and multinuclear solid-state Nuclear Magnetic Resonance (ssNMR). Perhaps counterintuitively, pressurization tends to increase the concentration of three-coordinated boron species (B(III) units) at the expense of four-coordinated boron (B(IV) units). 23Na NMR spectra show a systematic shift toward higher frequencies in the pressurized glasses, consistent with shorter average Na-O distances. The results are consistently explained in terms of a breakage of Si-O-B4 linkages resulting in the formation of nonbridging oxygen species. Pressure effects on the spectra are reversed by annealing the glasses at their respective glass transition temperatures.

Effect of modifier cation size on the structure, properties and nickel speciation in BK7 type alkali borosilicate glasses

Effect of modifier cation size on the structure, properties and nickel speciation in BK7 type alkali borosilicate glasses

Effects of reducing atmosphere and iron content on UV transmission property of alkali-silicate and alkali-borosilicate glasses

The effects of the reducing atmosphere during glass melting and the iron content in glass on the ultraviolet (UV) transmission property of borosilicate and silicate glasses were studied. The reducing atmosphere is controlled by the amount of citric acid in each glass batch. The effects of reducing atmosphere on the glass UV transmittance were examined in terms of the distribution of trigonal boron (BO3) and tetrahedral boron (BO4) units and iron reduction index (IRI). Our study reveals that the reducing atmospheres not only had a significant effect on the boron-oxygen structure of alkali-borosilicate glass, but also on the UV transmittance. In addition, IRI has a significant effect on the UV transmittance at a wavelength of 254 nm, with a relative change up to 461%. The iron oxidation state was found to affect the UV absorption coefficient of ferric ion (Fe(III) has about four times greater than that of ferrous ion (Fe(II)) at 254 nm.

On the Formation of Nanogratings in Commercial Oxide Glasses by Femtosecond Laser Direct Writing.

Nanogratings (NGs) are self-assembled subwavelength and birefringent nanostructures created by femtosecond laser direct writing (FLDW) in glass, which are of high interest for photonics, sensing, five-dimensional (5D) optical data storage, or microfluidics applications. In this work, NG formation windows were investigated in nine commercial glasses and as a function of glass viscosity and chemical composition. The NG windows were studied in an energy—frequency laser parameter landscape and characterized by polarizing optical microscopy and scanning electron microscopy (SEM). Pure silica glass (Suprasil) exhibits the largest NG window, whereas alkali borosilicate glasses (7059 and BK7) present the smallest one. Moreover, the NG formation windows progressively reduced in the following order: ULE, GeO2, B33, AF32, and Eagle XG. The NG formation window in glasses was found to decrease with the increase of alkali and alkaline earth content and was correlated to the temperature dependence of the viscosity in these glasses. This work provides guidelines to the formation of NGs in commercial oxide glasses by FLDW.

Influence of Microstructure on Color Tone of Heat-Treated Red Paint Composed of Lead-Free Multicomponent Alkali Borosilicate Glass Frit and Hematite

Influence of Microstructure on Color Tone of Heat-Treated Red Paint Composed of Lead-Free Multicomponent Alkali Borosilicate Glass Frit and Hematite

Glass as a State of Matter—The “newer” Glass Families from Organic, Metallic, Ionic to Non-silicate Oxide and Non-oxide Glasses

OVERVIEWIn theory, any molten material can form a glass when quenched fast enough. Most natural glasses are based on silicates and for thousands of years only alkali/alkaline earth silicate and lead-silicate glasses were prepared by humankind. After exploratory glass experiments by Lomonosov (18th ct) and Harcourt (19th ct), who introduced 20 more elements into glasses, it was Otto Schott who, in the years 1879–1881, melted his way through the periodic table of the elements so that Ernst Abbe could study all types of borate and phosphate glasses for their optical properties. This research also led to the development of the laboratory ware, low alkali borosilicate glasses. Today, not only can the glass former silicate be replaced, partially or fully, by other glass formers such as oxides of boron, phosphorous, tellurium or antimony, but also the oxygen anions can be substituted by fluorine or nitrogen. Chalcogens, the heavier ions in the group of oxygen in the periodic table (S, Se, Te), on their own or when paired with arsenic or germanium, can function as glass formers. Sulfate, nitrate, tungstate and acetate glasses lack the conventional anion and cation classification, as do metallic or organic glasses. The latter can occur naturally—amber predates anthropogenic glass manufacture by more than 200 million years.In this chapter, we are going to provide an overview of the different glass families, how the structure and properties of these different glass types differ from silicate glasses but also what similarities are dictated by the glassy state. Applications and technological aspects are discussed briefly for each glass family.

A full-scale tracing study of "ghost peaks" encountered in impurity analysis of budesonide based on experimental operation inspection-liquid chromatography/mass spectrometry fingerprint-mechanism based stress studies integrated strategy.

Budesonide is an active pharmaceutical ingredient used in various dosage forms of finished products for the treatment of asthma. During the process of drug development, unbiased analysis of related substances is of utmost significance for both pharmaceutical research and quality control purposes. In this work, the official method documented in the United States Pharmacopoeia was selected to determine the related substances of budesonide considering the pros and cons of critical chromatographic parameters, compared to the European Pharmacopoeia. In doing so, several unpredictable interference peaks, namely "ghost peaks", were observed occasionally during analysis. A strategy that integrated information derived from experimental operation inspection, liquid chromatography/mass spectrometry fingerprint analysis, and mechanism-based stress studies was then proposed for comprehensively and quickly exploring those non-degradable and degradable peaks. Some ghost peaks were found to originate from nylon syringe filter, illumination, and alkali borosilicate glass high-performance liquid chromatography vials. Besides, degradation pathways under alkaline conditions were also unraveled through liquid chromatography-mass spectrometry qualitative analysis. Overall, an optimization of the analytical methodology based on the United States Pharmacopoeia for its application in impurity analysis of budesonide and corresponding formulations was carried out with the design of experiments, by which "ghost peaks" could be suppressed or prevented. The results obtained herein are not only crucial to studies on budesonide's stability or degradation kinetics but also contribute to clarifying the impurity research of other drugs.

Effects of sulfur and potassium on rhenium retention in simplified low-activity waste glass

Four consecutive sets of simplified glass feed compositions were designed and tested both with and without rhenium (Re) additions. The objectives of this study concerning the effects of sulfur (S, expressed as SO3 in glass) and potassium (K, K2O in glass) on Re retention during melting of low-activity glass feeds were twofold: (i) design a simplified system that reproduces the Re behavior observed in fully simulated feeds, the system will be used to investigate mechanisms related to Re incorporation into glass and (ii) Provide experimental data that support or reject the mechanisms that have been proposed to explain the previous findings from scaled melter and crucible tests. The simplified system of alkali borosilicate glass feeds in this study successfully reproduced the published results from the melter tests with fully simulated feeds on the effects of S and K on Re behavior. The present study also provides experimental evidence on the combined effect of S and K. The findings from this study regarding the effects of S and K on Re retention also are explained by the previously proposed mechanism on the effect of sulfate on Re retention and by the effect of component concentrations and activity coefficients of volatile species on its vapor pressure, also discussed in a recent study.

Chemical structure and dissolution behaviour of CaO and ZnO containing alkali-borosilicate glass

Altering the CaO to ZnO ratio of alkali borosilicate glass, in favour of ZnO, causes phase separation with hardystonite-like (Ca2ZnSi2O7) and willemite-like (ZnSi2O4) structures identified. This is concurrent with increased glass durability.

Structural transition and temperature dependencies of thermal expansion coefficients of NaNO-=SUB=-3-=/SUB=- embedded into the nanoporous glass

The temperature evolution of the crystal structure of a nanocomposite material obtained by introducing sodium nitrate NaNO3 from a melt under pressure into a nanoporous alkali borosilicate glass with an average pore diameter of 7 nm has been studied by the method of diffraction of synchrotron radiation in a wide temperature range upon heating. Analysis of the experimental diffraction patterns revealed a significant decrease in the temperature of the structural (orientational) transition by more than 50 K (up to 496 K) compared to bulk sodium nitrate. From the temperature dependence of the intensity of the superstructure peak (113), the dependence of the critical exponent β(T) for this transition was obtained and a significant difference from the critical exponent for a bulk material was found in the temperature range from 455 K to the transition temperature. Analysis of the broadening of Bragg reflections made it possible to estimate the average size (~40 nm) of sodium nitrate nanoparticles into the pores. An increase in the linear coefficient of thermal expansion in the [001] direction was found in NaNO3 nanoparticles in comparison with bulk material at temperatures above 450 K. Keywords: porous glasses, phase transitions, nanocomposite materials, synchrotron radiation diffraction, sodium nitrate, restricted geometry, structure, size effects.

Структурный переход и температурные зависимости коэффициентов теплового расширения NaNO-=SUB=-3-=/SUB=-, внедренного в нанопористое стекло

The temperature evolution of the crystal structure of a nanocomposite material obtained by introducing sodium nitrate NaNO3 from a melt under pressure into a nanoporous alkali borosilicate glass with an average pore diameter of 7 nm has been studied by the method of diffraction of synchrotron radiation in a wide temperature range upon heating. Analysis of the experimental diffraction patterns revealed a significant decrease in the temperature of the structural (orientational) transition by more than 50 K (up to 496 K) compared to bulk sodium nitrate. From the temperature dependence of the intensity of the superstructure peak (113), the dependence of the critical exponent β (T) for this transition was obtained and a significant difference from the critical exponent for a bulk material was found in the temperature range from 455 K to the transition temperature. Analysis of the broadening of Bragg reflections made it possible to estimate the average size (~ 40 nm) of sodium nitrate nanoparticles into the pores. An increase in the linear coefficient of thermal expansion in the [001] direction was found in NaNO3 nanoparticles in comparison with bulk material at temperatures above 450 K.

Hematite crystal growth in high-temperature lead-free multicomponent alkali borosilicate glass frit for red overglaze enamels

To elucidate the crystal growth process of hematite in high-temperature lead-free multicomponent alkali borosilicate glass, which is essentially important to control the color of red overglaze enamels, frit and hematite mixture is heat-treated and subjected to microscopic observations. Hematite particles slightly grew due to sintering at low temperature. Once the glass matrix formed near the softening point of frit, hematite dissolved into glass fluid. Hematite crystal growth concomitantly ensued with decrease in the number of hematite particles via Ostwald ripening as the temperature increased. The grown particles exhibited an anisotropic morphology with straight outlines reflecting crystal planes, the morphology of which is completely different from those grown by sintering and particles prior to heating. These results suggest that comprehensive understanding of frit and hematite from the perspectives of glass science and chemistry as well as powder technology are important to truly control the color of red overglaze enamels.

Simultaneous quantification of low Z elements in phosphorus containing alkali borosilicate glass samples by in situ Current normalized external (in air) PIGE method utilizing proton beam from FOTIA

An attempt was made to increase the solubility of High Level liquid Waste (HLW), mainly Cr and Mo, by addition of P2O5 to sodium borosilicate glass. A total of seven different phosphorus containing alkali borosilicate glass samples were in-house fabricated. As a part of chemical quality control, concentrations of four low Z elements namely Si, Na, B and P were determined by in situ current normalized external (in air) Particle Induced Gamma-ray Emission (PIGE) method using low energy proton beam from Folded Tandem Ion Accelerator (FOTIA), BARC. PIGE method was validated by analyzing synthetic elemental standards and suitable certified reference materials. Phosphorus has shown thermal losses during fabrication.

All-glass micro-groove light guide plate by mask and etch

All-glass, micro-groove arrays were etched into a glass light guide plate surface, transforming edge-lit incident light into uniform area output from its surface. All micro-grooves in the array shared similar shape and extraction efficiency. They were spray etched into Corning alkali-borosilicate glass (Iris) effectively controlling the degree of light extraction uniformity along the array’s normal direction by varying the inter-groove pitch from 300–1000 µm. Luminance uniformities in excess of 80% for 9-point, or 75% for 455-point measurements were achieved with 1.2% extraction efficiency per groove. Enhanced light redirection from individual micro-grooves towards normal viewing reduced number of additional beam steering films required in light guide plate, backlight units.

Studying the Toxicity of High-Silica Porous Glass by Biotesting

The article presents the results of a study of the biological activity of porous high-silica glass obtained based on two-phase alkali borosilicate glass. The test results show that the toxicity of the investigated porous glass (PG) in relation to Paramecium caudatum varies depending on the concentration and time of contact of the finely dispersed PG powder with water. It is assumed that the revealed pattern is related to, first of all, the extraction of alkaline ions into an aqueous solution.

Низкотемпературная аномалия диэлектрических свойств наночастиц магнетита

This paper is devoted to study the dielectric response of magnetic alkali borosilicate glasses containing single-domain magnetite nanoparticles in the temperature range 5 - 100 K on heating and on cooling in magnetic fields from 0 to 14 T in the frequency range from 1 Hz to 160 kHz. It is shown, that an anomaly in the dielectric response is observed in the temperature range 15 - 50 K for single-domain magnetite nanoparticles. The position of this peculiarity is in good agreement with the transition to the relaxor state observed in the bulk material. The temperature hysteresis of this anomaly has been observed on heating and cooling, and it decreases with decreasing measurement frequency.

A NMR and SANS study of alkali-borosilicate behaviour under thermal neutron irradiation

The internal structure of several alkali-borosilicate glasses has been studied when exposed to a high thermal neutron flux. More specifically, the different glasses we are interested in are widely used around the globe for neutron guide manufacturing and show drastically different resistance to irradiation. Samples were irradiated with the thermal flux from T4 experimental tube in ILL’s High Flux Reactor up to a fluence of several 1017 n/cm2. The experimental tools employed for the structural analysis were Nuclear Magnetic Resonance (NMR) and Small Angle Neutron Scattering (SANS). NMR measurements allowed to detect the modification of atoms’ close environment and these results have been correlated to evolutions at macroscopic scale. In addition, neutron scattering measurements have demonstrated the possibility to detect phase segregation in a zinc-alkali-borosilicate.