International Journal of Applied Glass Science最新文献

Lead-containing alkali/alkaline-earth borate and barium lead phosphate glasses were prepared by melt-quenching for a detailed investigation of the Pb²⁺ ions’ optical properties. UV–Vis absorption and photoluminescence spectroscopy reveal variations in the s–p transition of Pb²⁺, which are shown to correlate with the optical basicity of the host glass in both borates and phosphates. Pb²⁺ emission differs significantly for borate and phosphate glasses, as the nature of the charged sites available to accommodate Pb²⁺ cations vary. Optical basicity values were determined from the composition (Λ_th) and the measured refractive index (Λ_n). The UV-cutoff shifts toward higher wavelengths with increasing optical basicity and lead content. In borate glasses, the frequency of the stretching modes due to nonbridging oxygen atoms of trigonal metaborate species is identified to be inversely proportional to the excitation wavelength (directly proportional to the excitation energy) of Pb²⁺. Lead-containing alkali and alkaline-earth borate glasses show additional correlations between the Pb²⁺ emission wavelength and the weighted average of the field strength of the modifier(s). Complementary to the investigation of optical properties, radiation and neutron shielding parameters were calculated, suggesting the potential utility of some of the studied compositions for radiation shielding applications.

In this study, glasses in composition 70WO₃–(30 − х)P₂O₅–хB₂O₃ (0 ≤ х ≤ 20 mol%) were prepared by melt quenching method. The glass formation, structure, and thermal and electrical properties are discussed. Homogeneous glasses were obtained at x = 0–10 mol% B₂O₃, whereas glasses with x = 15 and 20 contain microinclusions of WO₃. The glass transition temperature decreases from 709 to 531.6°C with increasing B₂O₃ content, as well as the crystallization temperature and the thermal stability. The structure of the glasses was studied by Raman spectroscopy and infrared spectroscopy. The Raman spectra are characterized by a band near 995 cm⁻¹, a broad band at 788–800 cm⁻¹, and a band near 675 cm⁻¹ ascribed to vibrations of W–O–P, W–O–W, and P–O–B bonds, respectively. The Fourier-transform infrared spectra show vibrational bands due to characteristic phosphate and borate groups. Tetrahedral BO₄ units prevail in the structural network. The electrical conductivity of the glasses decreased with x content due to the growth of WO₃-deficient regions.

In the study of deep geological disposal of high-level radioactive waste (HLW), beta decay has been widely studied, whereas the nuclear transmutation effects due to beta decay on vitrification are generally neglected. In this work, a series of sodium borosilicate glasses doped with cesium was fabricated. The nuclear transmutation due to beta decay evolving with the deposited time was simulated by substituting for cesium with barium. The macroscopic properties of the glasses, including density, hardness, and Young's modulus, were measured using the Archimedes (buoyancy) method and nanoindentation, respectively. The microscopic structures of the glasses were characterized by grazing incident X-ray diffraction, infrared spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and Raman spectroscopy. The nuclear transmutation effects were significant. With the substitution of barium for cesium, the density, hardness, and modulus of the glasses increased and eventually tended to saturation. A decrease of [BO₃] units and an increase of [BO₄] units were observed in the infrared spectra and NMR spectra. In addition, the results were systematically compared to previous strontium-doping work in order to evaluate nuclear transmutation effects due to beta decay on vitrification in HLW comprehensively. The comparison demonstrated that the nuclear transmutation effect of cesium is completely opposite to that of strontium. The research is expected to contribute to a deeper understanding on the nuclear transmutation effects due to beta decay in HLW on vitrification.

The relationship between sintering and glass-to-metal bonding, which are almost the initial and the last stages of glass-to-metal seal production, has been demonstrated in this study. In this context, a type of barium alkali silicate glass was prepared, and thermal properties were determined by differential thermal analysis, dilatometer, hot-stage microscope, and high-temperature viscosity analysis. Detailed porosity investigations were examined with an optical microscope and ImageJ quantitative analyses, after binder removal and sintering processes carried out at different temperatures and times. An increase in porosity was observed when the sintering and binder removal temperatures and times were increased. The bending strength of the sintered glass sample was decreased with the increment in porosity. A typical housing material AISI 316L stainless steel was used for preparing glass-to-metal joints. The high porosity after sintering caused larger bubbles to form after bonding and reduced the shear strength. The effect of sintering conditions on the interfacial interaction for glass-to-metal joints are revealed by cross-sectional scanning electron microscopy–energy-dispersive spectrometer analyses. Atomic force microscopy analyses and contact angle measurements were conducted to supplement investigation. This study addressed that the mechanical strength and chemistry of glass-to-metal joints showed strong dependency on glass sintering conditions.

As borosilicate glasses are used in many countries to immobilize fission products and minor actinides after spent fuel reprocessing before storage in a deep geological repository, assessing that their chemical durability is of paramount importance. Here, pristine and preirradiated (952 MeV, 136Xe) SiO₂–B₂O₃–Al₂O₃–Na₂O glasses with the same molar ratios as in the French SON68 and ISG glasses have been subjected to aqueous corrosion in deionized water and in silica-saturated solution to measure the initial and longer term alteration rates. Pristine and preirradiated glasses corrode following the same mechanisms, but the preirradiation has a strong impact on the initial dissolution rate (increase by a factor of 5.6), and on the alteration layer depth in silica-saturated conditions (by two- to threefolds). The later result is related to the formation of a more porous, less passivating gel on the preirradiated glass specimen. Using both experimental spectroscopies (NMR, IR, and SFG) and classical molecular dynamics, the radiation effects on the glass structure and water diffusion have been assessed. After preirradiation, the density and the polymerization degree of the glass decrease, whereas the topological disorder increases. In consequence, water diffusion accelerates. These observations allow to correlate the radiation impact on the alteration behavior to the structural changes.

Chalcogenide glasses (ChGs) are technologically superior materials, and their properties underpin the demands of whispering gallery mode–based integrated photonic devices. The prime focus of this review is to showcase the recent advances in the field of ChG high Q cavities. The review also covers the theoretical research aspects and brief on the research challenges and limitations involved in the topic.

Thermally stimulated interactions between silver and glass, that is, silver dissolution as Ag⁺ and precipitation as Ag⁰ were studied in two glass series of molar target composition xAg₂O–(19 − x)Na₂O–28ZnO–53B₂O₃ with x = 0, 0.1, 0.5, 5 and (19Na₂O–28ZnO–53B₂O₃)+yAg₂O with y = 0.01, 0.05. These act as model for low-melting borate glasses being part of metallization pastes. The occurrence of metallic silver precipitates in melt-quenched glass ingots demonstrated that silver dissolved only in traces (< 0.01 mol%) in the glasses. The dissolved silver was detected by means of Raman spectroscopy and energy-dispersive X-ray spectroscopy. Increasing x in the batch could not lead to a significant increase of the silver ion fraction in the glass as possible in binary silver borate glasses. In situ observation of heated AgNO₃ mixed with the base glass frit in a hot stage microscope showed that Ag⁰ precipitation occurs already at the solid state. At higher temperatures, small droplets of liquid silver were found to move freely within the melt, whereas coalescence caused a stepwise increase of their size. These results contribute to the understanding of formation of silver precipitates in metallization pastes described in the literature.

A predictive model of melt rate in waste glass vitrification operations is needed to inform melter operations during normal and off-normal operations. This paper describes the development of a model of the cold cap (the reacting melter feed floating on molten glass in a glass melter) that couples heat transfer with the feed-to-glass conversion kinetics. The model was applied to four melter feeds designed for high-level and low-activity nuclear waste feeds using the material properties, either measured or estimated, to obtain temperature and conversion distribution within the cold cap. The cold cap model, when coupled with a computational fluid dynamics model of a Joule-heated glass melter, allows the prediction of the glass production rate and power consumption. The results show reasonable agreement with the melting rates measured during pilot-scale melter tests.