Field strength effect on elastoplastic behavior of aluminoborosilicate glass: II. Volumetric recovery

The field strength (FS) effect of six different network modifiers on the elastoplastic properties of aluminoborosilicate glasses was explored using a volumetric recovery study. This work, in conjunction with Part I, explored the intersection of hardness, crack resistance, and other physical properties with glass elasticity. Results showed that (1) the elastic volume fraction decreased with FS for both the alkali and alkaline earth (AE) glasses; (2) the Poisson's ratio did not trend with pile-up or shear flow volume fraction; (3) the elastic-to-plastic deformation ratio increased with applied load and decreased with modifier FS for both the alkali and AE glasses; and (4) an increase in plasticity correlated with increased hardness, crack resistance, and elastic moduli.     

Enhancement of emission intensity in Ce3+-activated aluminoborosilicate scintillating glass synthesized in air

A highly effective method of synthesizing transparent and colorless Ce³⁺-activated aluminoborosilicate glass in air by high temperature melt-quenching is reported. This is achieved by partial substitution of AlN for Al₂O₃ without using any reduction in atmosphere. The optimized Ce³⁺-activated aluminoborosilicate scintillating glass is featured with a density of ~4.5 g/cm³ and a lifetime of 41.74 ns. Compared to the glass synthesized without AlN substitution, both the photo and raidoluminescence intensity of the optimized Ce³⁺-activated aluminoborosilicate scintillating glass are enhanced by a factor of 24.4 and 6.76, respectively. The corresponding integrated raidoluminescence intensity is about 17.6% of that of BGO crystal under X-ray excitation at 30 kV and 3 mA, respectively.     

Ab initio molecular dynamics simulation of the structural and electronic properties of aluminoborosilicate glass

In this study, the structural and electronic properties of aluminoborosilicate glass, which has a wide range of applications in fields such as microelectronics and displays, were examined using ab initio molecular dynamic simulations. Computing models containing 220 atoms correctly described the local structure of the glass. The reliability of the computing models was verified by the consistency between the experimental results, obtained using high-energy X-ray diffraction and solid-state nuclear magnetic resonance, and the simulation results pertaining to structural factors, pair distribution functions, Qⁿ distribution, and elastic properties. The presence of B and Al increased the flexibility and asymmetry of the system, as shown by the bond angle and ring size distributions. Based on the electronic properties, we observed that the introduction of Al and B atoms into the network could also cause covalent interactions with the O atoms, similar to that with Si atoms. However, the Na and Mg atoms still interacted with all kinds of atoms in the network via charge transfer and exhibited highly non-localized effects on the charge of the network formers. These results extend our understanding of the structure of aluminoborosilicate glass and have guiding significance for improving and designing new types of this glass.     

Field strength effect on elastoplastic behavior of aluminoborosilicate glass: I. Elastic moduli and indentation size effect

The modifier field strength (FS) is believed to play an important role in determining the elastic–plastic responses of aluminoborosilicate (ABS) glasses, but its effect is not well understood. Three novel alkali and three alkaline earth (AE) ABS compositions were created for this study which is the first part of two studies that explored the elastoplastic responses of these glasses. Six compositions were designed using different network modifiers (NWMs) to cover a range of cation FS. The glasses were also designed such that the concentrations of NWM and Al₂O₃ were similar, which maximized the three-coordinated boron fraction in the network. It is well known that modifier FS can affect the coordination number (CN) of Al and B in an ABS glass structure, for example, a higher FS modifier can promote B³ → B⁴ and higher [Al^5,6], but the degree of this depends on network former (NWF) ratios. Previous work used solid-state NMR spectroscopic analysis on the current glasses to find that there was variation between [B⁴] and [Al⁴] between the two glass series (alkali vs. AE) but that was attributed to synthesis factors and no trend with FS was associated with the varying NWF CN. Further, ²⁹Si ssNMR showed no evidence of NBOs which made sense based on composition. The conclusion, therefore, was that there was a far greater correlation with modifier FS for the increased mechanical and physical properties rather than the CN of Al and B. Part I of the current work focused on the elastic moduli, Poisson's ratio, the indentation size effect (ISE), and the bow-in parameter. This part laid out the foundation to investigate the intersection of these elastoplastic properties with hardness and crack resistance as a function of NWM FS. Results showed that: (i) the Young's, bulk, and shear moduli increased with modifier FS, whereas Poisson's ratio did not trend with FS; (ii) the alkali glasses had a significantly higher magnitudes of ISE compared to the AE glasses; and (iii) the bow-in parameter was load dependent and decreased with modifier FS at the highest indentation load.     

Field strength effect on structure,hardness, and crack resistance in single modifier aluminoborosilicate glasses

Although the interactions among glass formers and modifiers, for example, connectivity and charge distribution, have been studied extensively in oxide glasses, the impact of a particular modifier species on the mechanical performance of aluminoborosilicate (ABS) glasses is not well understood. This work compares the indentation properties of six ABS glasses, each of which contains a different network modifier (NWM) with varying field strength (FS). Three alkali and three alkaline earth ABS glasses were designed with low NWM content and [NWM] ≈ [Al₂O₃], to test the modifier FS effect at low concentrations and to maximize three-coordinated boron. It has been found that both hardness and crack resistance increase with increasing FS in these ABS systems, which is surprising in the context of historical reports. Using ¹¹B, ²⁷Al, and ²⁹Si solid-state nuclear magnetic resonance, this work provides evidence of how charge distributions differ as a function of NWM species, and how this relates to the observed indentation behaviors.     

Study on the blackening phenomenon of leaded glass during microgroove molding using nickel phosphorous mold

Precision glass molding (PGM) is a recently developed method to fabricate glass microgroove components. Lead glass is commonly used as an optical material due to its high refractive index and low transition temperature. A nickel-phosphorous (Ni–P) plated mold is traditionally employed in the PGM process for microstructures optics. However, leaded glass is subject to color change and can blacken during the PGM process, reducing the light transmittance of microgrooves. In this paper, an equation for the redox reaction between Ni and Pb is proposed, which is based on the diffusion of inner Ni atoms to the surface of the mold and the standard electrode potential of the Pb ions in leaded glass. A viscoelastic constitutive model of the glass is established to simulate the compression stress distribution during molding. Finally, the effects of molding pressure, molding temperature, and mold material on glass blackening are studied. The results show that the blackening of leaded glass is caused by Pb enriching the surface. The rise in molding stress and temperature increases the deformation of Ni–P plating, which promotes the diffusion of Ni atoms. By adding a titanium incorporated diamond-like carbon (Ti-DLC) coating, the deformation of the Ni–P plating during molding is suppressed, and the diffusion of Ni atoms can be prevented. In this way, the blackening of leaded glass can be prevented.     

Structural drivers controlling sulfur solubility in alkali aluminoborosilicate glasses

If the direct feed approach to vitrify the Hanford's tank waste is implemented, the low activity waste (LAW) will comprise higher concentrations of alkali/alkaline-earth sulfates than expected under the previously proposed vitrification scheme. To ensure a minimal impact of higher sulfate concentrations on the downstream operations and overall cost of vitrification, advanced glass formulations with enhanced sulfate loadings (solubility) are needed. While, the current sulfate solubility predictive models have been successful in designing LAW glasses with sulfate loadings <2 wt.%, it will be difficult for them to design glass compositions with enhanced loadings due to our limited understanding of the fundamental science governing these processes. In this pursuit, this article unearths the underlying compositional and structural drivers controlling the sulfate solubility in model LAW glasses. It has been shown that the preferentially removes non-framework cations from the modifier sites in the silicate network, thus, leading to the polymerization in the glass network via the formation of ring-structured borosilicate units. Furthermore, though the sulfate solubility slightly decreases with increasing Li⁺/Na⁺ in the glasses, the prefers to be charge compensated by Na⁺, as it is easier for to break Na–O bonds instead of Li–O bonds.     

Structural dependence of crystallization in phosphorus-containing sodium aluminoborosilicate glasses

The article reports on the structural dependence of crystallization in Na₂O–Al₂O₃–B₂O₃–P₂O₅–SiO₂-based glasses over a broad compositional space. The structure of melt-quenched glasses has been investigated using ¹¹B, ²⁷Al, ²⁹Si, and ³¹P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, while the crystallization behavior has been followed using X-ray diffraction and scanning electron microscopy combined with energy dispersive spectroscopy. In general, the integration of phosphate into the sodium aluminoborosilicate network is mainly accomplished via the formation of Al–O–P and B–O–P linkages with the possibility of formation of Si–O–P linkages playing only a minor role. In terms of crystallization, at low concentrations (≤5 mol.%), P₂O₅ promotes the crystallization of nepheline (NaAlSiO₄), while at higher concentrations (≥10 mol.%), it tends to suppress (completely or incompletely depending on the glass chemistry) the crystallization in glasses. When correlating the structure of glasses with their crystallization behavior, the MAS NMR results highlight the importance of the substitution/replacement of Si–O–Al linkages by Al–O–P, Si–O–B, and B–O–P linkages in the suppression of nepheline crystallization in glasses. The results have been discussed in the context of (1) the problem of nepheline crystallization in Hanford high-level waste glasses and (2) designing vitreous waste forms for the immobilization of phosphate-rich dehalogenated Echem salt waste.     

Green synthesis of copper-doped nickel oxide nanoparticles using okra plant extract for the evaluation of their cytotoxicity and photocatalytic properties

Considering the significant role of metal nanoparticles in the detection and removal of pollutants from the environment, metal oxides stand as inexpensive materials at the scale of nanometers that are capable of participating in photocatalytic and decontamination procedures. Meanwhile, nickel nanoparticles have been applied as a new approach for removing the existing pollution from the environment. In this paper, we have synthesized copper doping nickel oxide nanoparticles (Cu-doped NiO-NPs) by a sol-gel method that involved the application of okra plant extract and had investigated their photocatalytic properties and cytotoxicity effects. The obtained Cu-doped NiO-NPs have been characterized through FT-IR, UV–Vis, XRD, FESEM/EDAX/PSA, and VSM analyses in different concentrations (1, 3, and 5%) of copper at an optimum temperature of 400 °C. According to the XRD results, the size of nanoparticles under optimal conditions (at the temperature of 400 °C and % 3 Cu-doped) has been observed to be 10.66 nm while containing a face-centered cubic (fcc) structure. Furthermore, the obtained FESEM outcomes have been indicative of the good dispersion of these nanoparticles. Also, photocatalytic activity of Cu-doped NiO-NPs through the degradation of methylene blue (MB) pigment studied under UV-A light and had detected 78% of degradation throughout 105 min. To complete the characterization process, the cytotoxicity of nanoparticles in inhibiting the cancer CT26 cells has been determined using of MTT assay.     

Structure-property relations in crack-resistant alkaline-earth aluminoborosilicate glasses studied by solid state NMR

The effect of the average ionic potential ξ = Ze/r of the network modifier cations on crack initiation resistance (CR) and Young's modulus E has been measured for a series of alkaline-earth aluminoborosilicate glasses with the compositions 60SiO₂–10Al₂O₃–10B₂O₃–(20−x)M₍₂₎O–xM’O (0 ≤ x ≤ 20; M, M’ = Mg, Ca, Sr, Ba, Na). Systematic trends indicating an increase of CR with increasing ionic potential, ξ, have been correlated with structural properties deduced from the NMR interaction parameters in ²⁹Si, ²⁷Al, ²³Na, and ¹¹B solid state NMR. ²⁷Al NMR spectra indicate that the aluminum atoms in these glasses are essentially all four-coordinated, however, the average quadrupolar coupling constant <C_Q> extracted from lineshape analysis increases linearly with increasing average ion potential computed from the cation composition. A similar linear correlation is observed for the average ²⁹Si chemical shift, whereas the fraction of four-coordinate boron decreases linearly with increasing ξ. Altogether the results indicate that in pure alkaline-earth boroaluminosilicate glasses the crack resistance/E-modulus trade-off can be tailored by the alkaline-earth oxide inventory. In contrast, the situation looks more complicated in glasses containing both Na₂O and the alkaline-earth oxides MgO, CaO, SrO, and BaO. For 60SiO₂–10Al₂O₃–10B₂O₃–10MgO–10Na₂O glass, the NMR parameters, interpreted in the context of their correlations with ionic potentials, are consistent with a partial network former role of the MgO component, enhancing crack resistance. Altogether the presence of MgO in aluminoborosilicate glasses helps overcome the trade-off issue between high crack resistance and high elasticity modulus present in borosilicate glasses, thereby offering additional opportunities for the design of glasses that are both very rigid and very crack resistant.     

Heat treatment to regulate bismuth valence toward enhanced radiation resistance in barium gallo-germanate glass

Due to the excellent infrared transparency, low phonon energy, and high rare-earth solubility, germanate laser glass has attracted much attention in mid-infrared fiber lasers for potential coherent laser radar systems, optical detection, remote sensing, and laser surgery. However, radiation-induce darkening often occurs in fiber lasers that operate in radiation environment. Here, we report a useful strategy to improve the radiation resistance by adding multivalence Bi ions and discuss its radiation resistance mechanism. In order to study the effect of valence states on the radiation resistance of barium gallo-germanate glass, we adjust the valence states of Bi ions by heat treatment, the potential mechanism of which is discussed in detail based on the absorption, photoluminescence (PL), and Raman spectra. The absorption, electron paramagnetic resonance, and photoluminescence spectra have proved the interconversion of Bi ions between low and high valence, which inhibits the formation of Ge-related electron center (GEC) and non-bridging oxygen hole center defects in the irradiation process. In addition, the Bi³⁺ content increased by heat treatment is beneficial to serve as electron-trapping centers in γ-ray irradiation, thus further reducing the formation of GEC. This study provides a simple method to achieve Bi valence regulation, so as to improve the radiation resistance.     

Efficient base-free oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid over copper-doped manganese oxide nanorods with tert-butanol as solvent

2,5-Furandicarboxylic acid (FDCA) is an important and renewable building block and can serve as an alternative to terephthalic acid in the production of bio-based degradable plastic. In this study, Cu-doped MnO₂ nanorods were prepared by a facile hydrothermal redox method and employed as catalysts for the selective oxidation of 5-hydroxymethylfurfural (HMF) to FDCA using tert-butyl hydroperoxide (TBHP) as an oxidant. The catalysts were characterized using X-ray diffraction analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy. The effects of oxidants, solvents, and reaction conditions on the oxidation of HMF were investigated, and a reaction mechanism was proposed. Experimental results demonstrated that 99.4% conversion of HMF and 96.3% selectivity of FDCA were obtained under suitable conditions, and tert-butanol was the most suitable solvent when TBHP was used as an oxidant. More importantly, the Cu-doped MnO₂ catalyst can maintain durable catalytic activity after being recycled for more than ten times.     

聚氨酯的辐射效应与辐射改性研究进展

本文讨论了聚氨酯的辐射效应,并综述了聚氨酯辐射改性的研究进展。     

辐射化学在煤加工中的应用

主要介绍了国内外用电离辐射强化煤加工过程的方法与进展,分析了煤脱硫、共热解、烟道气处理过程中应用的辐射化学原理,并提出了辐射化学原理应用于煤加工转化的新设想．     

The effect of lithium fluoride on the thermal stability and thermoluminescence properties of borosilicate glass and glass-ceramics

The oxyfluoride glass and glass-ceramics from the LiF-B₂O₃-SiO₂ system are developed. The stable glass can be produced in the range of 20–40 mol% LiF. The effect of LiF admixture on the thermal stability of the glass as well as the thermoluminescence (TL) properties such as glow curves shape is studied. The results show that the increase of lithium fluoride content in the borosilicate glass causes efficiency enhancement of the thermoluminescence signal. We have clearly stated that the process of controlled crystallization of the oxyfluoride glasses can lead again to increased intensity of the TL process. The glass-ceramics with 40 mol% LiF reveals similar level of TL signal to commercially used doped LiF material and can be considered as active material for alpha and beta radiation detectors.     

玻璃熔窑鼓泡技术

介绍了鼓泡技术强制熔化的作用和机理,指出了玻璃熔制选用鼓泡技术时应注意的几个问题。     

硼硅酸盐玻璃鳞片研制开发概况

叙述了我国玻璃鳞片的研究和开发历程，提出了厚度和表面处理的重要性。     

Production of alumino-borosilicate foamed glass body from waste LCD glass

A foaming process for waste LCD glass is presented, in which waste LCD glass is recycled to produce alumino-borosilicate foamed glass, which can eventually be used as a heat-insulating material, a light-weight aggregate for civil engineering applications, or a carrier for sewage treatment. The effects on waste LCD glass foaming of a variety of carbon foaming agents, metal salt foaming agents, and bonding agents are examined, as well as other factors such as chemical composition, foaming temperature, and grain size of the raw materials from the waste LCD glass. After examining all the variables that influence the foaming process, it was confirmed that the waste LCD glass is suitable as a raw material for producing alumino-borosilicate foamed glass. The alumino-borosilicate foamed glass has excellent physical properties, with density less than 0.14 g/cm³, heat conductivity less than 0.054 W/(mK) @20 °C, bending strength more than 35 N/cm², compressive strength more than 39 N/cm² and a coefficient of linear thermal expansion less than 4.5 × 10^?6 m/m °C. This clearly shows that the lightweight alumino-borosilicate foamed glass could be useful for various applications.