International Journal of Applied Glass Science最新文献

A series of Mn²⁺ single-doped 0.2Gd₂O₃-0.2Al₂O₃-0.6SiO₂ (GAS: xMn²⁺) glasses with Si₃N₄ as reducing agent were prepared. The presence of [SiO_4-x] defects and Mn²⁺ ions was determined from the absorption and excitation spectra of the glasses. With the increase of Mn²⁺ concentration, the intensity of blue emission decreases, while the intensity of red emission increases. The color coordinate of GAS: 6Mn²⁺ glass is (0.264, 0.226). The lifetime of the glasses was tested. Under the monitoring of 440 nm, the fast components (τ_f) are between 17 and 85 μs, and the slow components (τ_s) are between 200–650 μs. The former belongs to [SiO_4-x] defects, and the latter is [⁴E(G), ⁴A₁(G)]→⁶A₁(S) transition of Mn²⁺ ions. Under the monitoring at 630 nm, the τ_f are between 110 and 300 μs, and the τ_s are between 680 and 1220 μs, which are due to ⁴T₁(G)→⁶A₁(S) transition of Mn²⁺ ions and Mn²⁺ pairs, respectively. The energy transfer mechanism of [SiO_4-x] defect→Mn²⁺ ions are explained. The efficient [SiO_4-x] defect →Mn²⁺ ions energy transfer process was demonstrated by time-resolved photoluminescence, and the energy transfer efficiency is over 85%. The maximum photoluminescence quantum yield (PL QY) of the glasses can reach 15.87%. The thermal activation energy of the glasses was calculated. In addition, X-ray excited red luminescence spectra and the mechanism of the glasses were investigated.

Stainless steel slag waste can be used to prepare value-added glass ceramics, which can fix potentially toxic Cr from the slag within the crystalline phase. The occurrence and distribution of Cr during the preparation of glass ceramics has a great influence on the final Cr fixation effect. In this study, the effects of the TiO₂ content on the occurrence and distribution of Cr during the nucleation and crystallization steps and on the final properties of the glass ceramics were systematically studied. In the nucleation stage, with increasing TiO₂ content, the Cr distributed in the spinel containing chromium nuclei first increases and then decreases. In the crystallization stage, Diopside crystal phase nucleates and grows with spinel containing chromium nanocrystals as heterogeneous nuclei. X-ray photoelectron spectroscopy analysis showed that the chromium distributed in the diopside crystals first increased and then slightly decreased as the TiO₂ content increased. The optimal TiO₂ content is 3.4 wt.%, which resulted in 97 wt.% of the total Cr being fixed in the diopside crystalline phase (with a very low Cr leaching concentration of 0.009 mg/L), and a high compressive strength of the final glass ceramic of 267.4 MPa, and a Vickers hardness of 1211.8 HV. The research results provide theoretical and technical support for strengthening Cr fixation to enable harmless and high-value utilization of stainless steel slag for fabricating glass ceramics.

Experimental high temperature near infrared (NIR) absorption spectra of different SiO₂-based glasses, including lead silicate crystal glass, clear soda lime silicate (SLS) glass and fused silica with low and high OH content, are compared. The more polarizable the glass, the stronger is the increase in the high temperature NIR absorption at wavelengths < 2 µm, involving a red shift of the optical bandgap edge with increasing temperature. It appears that the modified glassy Urbach's rule provides a framework for describing the temperature red shift of the absorption edge of lead silicate crystal glass, even above T_g. This red shift causes a 4–7 times lower Rosseland thermal radiation conductivity of lead crystal glass melts compared to clear SLS glass melts. Low OH fused silica is practically transparent for NIR thermal radiation, also at high temperatures above T_g. Incorporation of water in fused silica increases the NIR absorption in the spectral region 1.7–3.4 µm, for all temperatures. An upper limit of the diffusion coefficient D of water in fused silica was estimated from the time to measure the high temperature NIR spectra of thin (∼2 mm) samples: D < 4 * 10⁻¹⁰ m²/s at temperatures up to around 2000°C.

Based on the current UK decarbonization policy, a general outlook on potential routes for the glass industry to achieve net-zero is discussed and the differentiation during decarbonization is specified. Biomass ash is considered a potential alternative raw material for low-carbon glass manufacture as it is rich in certain advantageous components, chiefly network modifiers. Simple sieving processes were shown to effectively separate impurities such as S, Cl, and C from some biomass ashes according to particle size distribution. The concentration of undesirable impurities decreased with increasing particle size. Morphologies and X-ray diffraction patterns of larger washed biomass ash particles indicated liquid/amorphous phase formation during biomass combustion. The washing of ashes was also shown to be a potential route to purification. A washed bracken ash relevant to both modern and ancient glass production was characterized for comparison. Ultraviolet-visible near-infrared (UV-Vis-near IR) absorption spectra of representative green container glasses produced using biomass ash confirmed that ∼5 wt.% ash in representative glass batches has little impact on the color and redox state of glasses; the redox status of glass produced using >2 mm biomass ash after washing was less reduced than that of glass produced using high levels (>∼9 wt.%) of >2 mm biomass ash after sieving alone, observed via the redox couple Cr³⁺/Cr⁶⁺ by UV-Vis-near IR absorption spectroscopy.

Bismuth-doped phosphosilicate fibers have become the most promising gain medium for O-band amplifiers. Yet scientific challenges on understanding the nature of bismuth active centers (BACs), mechanisms of bismuth cluster formation in the phosphosilicate glass network still exist. It is likely that multiple BACs with different oxidation states in different structural sites all contribute to the broad, nonsymmetric luminescence and gain spectra. Due to the progress in the fundamental understanding of bismuth-doped phosphosilicate glass, various designs of optical amplifiers with decent performances have been demonstrated.

We report the effect of high-repetition rate femtosecond (fs) laser irradiation on structure-terahertz (THz) property relationship for sodium borosilicate glasses. We have used nuclear magnetic resonance (NMR), terahertz time-domain spectroscopy (THz-TDS), and Raman spectroscopy to examine pristine and laser irradiated regions of these glasses to determine and quantify boron speciation, THz refractive index, n(THz), and change (Δn) in n(THz), and spectral, that is, structural, changes due to laser exposure, respectively. Our results suggest that laser irradiation-induced Δn(THz) values are dependent upon the glass composition, structural units, connectivity, and network, for example, the corresponding K- and R-values of the borosilicate glass. Depolymerized glass networks show no changes in NMR B₄ signal, slight changes in Raman spectral changes related to silicate structural units, for example, increase in Q³ tetrahedra with one nonbridging oxygen (nbO) atom, and higher measurable n(THz) and Δn(THz). More polymerized glasses, on the other hand, show changes in NMR B₄ signal, varying degrees of Raman spectral changes in the borate subnetwork and structural units, and lower n(THz) and Δn(THz). The THz refractive index is most sensitive to modifier ions in the glasses, which are directly responsible for nbO formation, glass structure, and network polymerization.

Borosilicate glass has been extensively studied due to its unique properties of solidifying high-level radioactive waste (HLW). However, the responses of borosilicate glass under γ irradiation are not fully understood. In this work, NBS9 and NBS10 glass were irradiated by γ-rays at absorbed doses of 8 kGy and 800 kGy, respectively. Scanning electronic microscopy, energy dispersive X-ray, and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to observe the surface morphology and elemental distributions. The results show that the borosilicate glass remains stable until the absorbed dose was up to 800 kGy. At 800 kGy, the samples precipitate particles composed of Na and O on the surface. Na and B near the surface are significantly reduced under γ-rays irradiation. The results indicate that the effects of γ irradiation on glass vitrification are obvious with certain accumulated doses. The changes of glass structures and elemental distributions by γ-ray irradiation are also dependent on glass compositions.

The paucity of crystallization resistant bioactive glasses with desired biological functions stands as a bottleneck toward the fabrication of various biomedical constructs such as amorphous coatings, scaffolds, and fibers for advanced tissue engineering applications. In this context, a series of borosilicate-based bioactive glasses with a range of compositions: (53.88 − x)SiO₂–21.7Na₂O–21.7CaO–1.7P₂O₅–xB₂O₃ (mol%) where x = 0, 13.47, 22.45, 31.43, and 40.41 were prepared to address such limitation. The glasses were primarily investigated for their potential to be processed into amorphous scaffolds through evaluation of crystallization kinetics, sintering behavior, and viscosity–temperature dependence. The inclusion of B₂O₃ gradually reduces the activation energy of crystallization (E_a), according to the prediction from different kinetic models, whereas Friedman's model-free method unraveled the variation in E_a as crystallization progresses. The crystallization event is further elucidated by obtaining the Avrami parameter (n) and dimensionality (m) through Matusita–Sakka equation. The optimization of the sintering schedule for amorphous scaffold preparation was accomplished by exploiting isothermal prediction from Avrami–Erofeev model. Moreover, viscosity–temperature relationship for the studied glasses was established to identify the processing window for drawing and sintering. This study proposes a comprehensive approach adopting theoretical models to elucidate suitable high-temperature process parameters of bioactive glasses avoiding devitrification.

A recently developed model of the cold cap—the reacting glass batch (melter feeds) floating on molten glass in an electric glass melter—couples heat transfer with the feed-to-glass conversion kinetics. The model allows for determining the distributions of temperature and various properties within the cold cap. In the present study, this model is applied to four melter feeds designed for high-level and low-activity nuclear wastes. Profiles of temperature, conversion degree, cold cap porosity and density, condensed matter velocity, and heating rate were determined using the material properties of the cold cap. Effects of vigorous foaming at the cold cap bottom were considered. Density, thermal conductivity, and glass production rate strongly affect the cold cap thickness and the fraction of undissolved silica entering the melt under the cold cap. The heating rate profile in the cold cap is highly nonlinear, with high heating rates observed in the foam layer.