International Journal of Applied Glass Science最新文献

Molecular dynamics simulations are performed to investigate the structural response of titania silicate glass to temperature. The coefficient of thermal expansion is computed for two titania silicate glasses with 0 and 10 mol% titania content, the structures of which are presented in terms of radial and angular distributions. Revealed by the different changing rates of intertetrahedra bond angles and bond lengths with respect to the Ti and Si atoms, the glass structures tend to exhibit a nonvectorized expansion process at elevated temperatures, leading to inconsistent expansion rates of the structures in different scales. While the average length of TiO and Si-O bonds both increases with temperature, the decrease in the coefficient of thermal expansion by the addition of Ti atoms is associated with the different expansion rate of tetrahedra. Arising from the gradual decrease in atomic overlapping, decrease in free volume inside the glass with temperature is also identified.

We compared the impact of alumina doping on the structure of Al₂O₃–SiO₂ amorphous thin films and bulk glasses using Raman spectroscopy and x-ray diffraction. In both thin films and bulk glasses, the addition of Al₂O₃ is accompanied by an increase in the mean Si–O–T angle and an evolution of the ring statistics with a decrease in the proportion of small rings. We evidenced structural differences between sputtered films and fused bulk glasses. Sputtered Al₂O₃–SiO₂ thin films are about 6%–7% denser than their equivalent Al₂O₃–SiO₂ bulk glasses. This difference is mainly due to a change in ring statistics with the formation of small rings within the sputtered thin films. These structural differences in atomic structural organization highlight the impact of the synthesis conditions and open the door to further investigation of the structure–functional property relationships in sputtered Al₂O₃–SiO₂ thin films.

Ytterbium-doped lanthanum titanate glasses were prepared by levitation melting for the detailed characterization of the $�{\mathrm{Yb}}^{�3�+�}$ spectroscopic properties in the rare-earth titanate glass host. Low-temperature fluorescence spectroscopy reveals distinct site-selectivity in both static and lifetime fluorescence measurements suggesting an absence of clustering as well as significant variation of local ytterbium environments. Typical site-selectivity behavior of a shrinking Stark manifold with lower excitation energy is observed. At 77 K, both the mean emission frequency and the fluorescence lifetime initially increase as the excitation energy decreases from about 11100 to 10750 $�{\mathrm{cm}}^{�-�1�}$ and then slightly decrease at lower excitation energy. Temperature-dependent lifetime measurements between 77 and 420 K show a decreasing lifetime with increasing temperature and are well described by a two-level thermal activation model. The temperature-dependent fluorescence spectroscopy coupled with a room temperature white light absorption measurement allow the determination of the Stark energy levels of $�{\mathrm{Yb}}^{�3�+�}$ in lanthanum titanate glass as well as the calculation of the laser cross-sections.

Control of sulfate-induced melt fining without excessive foaming is one of the critical steps in maintaining the stability of E-glass fiber manufacturing processes. Besides, the efficiency of combustion or energy utilization is directly affected by the extent of the melt-foaming. A fundamental understanding of key factors affecting melt foaming under the simulated oxy-fuel combustion environment will enable commercial E-glass fiber production to optimize both batch chemistry and operation conditions to achieve adequate furnace control. In this study, six types of E-glass batches with the same target glass composition were prepared by using four different CaO sources; calcined limes with different SO₃ contents, limestone, limestone with sodium sulfate, and a mixture of limestone and calcined lime. All batch samples were examined by HTMOS-EGA system (high temperature melting observation system with evolved gas analysis). HTMOS enables monitoring batch-to-melt conversation steps by using a high-resolution camera and EGA detects the evolved reaction gaseous, such as CO, CO₂, and SO₂ via an Fourier transform infrared (FTIR) gas analyzer. Gases of water vapor, N₂, and O₂ were introduced accordingly into the fused quartz crucible to simulate similar oxy-fuel atmosphere of the furnace operation. This study aimed to investigate the effects of different SO₃ contents in batches and different raw material chemistries on the foam formation in E-glass melts under the oxy-fuel atmosphere. Different raw materials were characterized by mineralogical analysis, chemical analysis, particle size distribution, chemical oxygen demanding (COD) level, and Brunauer–Emmett–Teller (BET) analysis. Although some of the batches contained the same SO₃ content, different foam formations resulted from the effect of the batch chemistry. Our detailed HTMOS-EGA investigations show that not only SO₃ content in the batch affects foam formation in E-glass melts, but also raw material chemistry and particle size have strong effects on the melt foaming in E-glass batch melting, especially for those of ingredients having hydroxide phases and/or finer particles with higher specific areas.

Topological constraint theory has emerged as a rapid, predictive method to quantify the relationship between structural rigidity and glass properties. Understanding the structure of telluro-vanadate (TeO₂–V₂O₅) glasses has remained difficult owing to their complex mixture of structural units. Here, we propose a topological model that accurately captures the glass structure and can be used to predict properties such as glass transition temperature and hardness. The experimentally obtained properties are in agreement with predicted properties by the model suggesting that this simplified structural model accurately describes the V₂O₅–TeO₂ structure.

Single (TiO₂) and complex (TiO₂ and ZrO₂) nucleating agents were added in CaO–Al₂O₃–SiO₂–ZnO–Na₂O–K₂O-based multicomponent glass to investigate its crystallization behavior and physical properties according to the types and amounts of nucleating agents. Nonisothermal analysis revealed crystallization behavior with an activation energy (E) of 165.176–518.985 kJ/mol and Avrami constant (n) of .73–2.12 with the complex nucleating agent. X-ray diffraction was used to observe the titanite and zircon crystalline phases in glass when using complex nucleating agents, and the crystallinity was found to be 43%–55%. Scanning electron microscopy and energy-dispersive x-ray spectroscopy were used to observe the plate-shaped titanite and column-shaped zircon crystalline phase in the glass matrix, and the glossiness was found to be decreased owing to the crystallization of the glass. The glass-ceramic showed a higher hardness and fracture toughness value of 6.45–6.7 GPa and 1.54–3.35 MPa∙m^1/2 when using the complex nucleating agent rather than when using the single nucleating agent.

Glasses in the TeO₂–Ga₂O₃–M₂O (M═Li, Na, or K) systems were synthesized by a melt-quenching technique. The glass forming areas were delimited for each system. Systematic analyses were performed on two series of samples—the first one with a constant TeO₂/Ga₂O₃ ratio of 85/15, that is, [(TeO₂)_0.85(Ga₂O₃)_0.15]_100−x[M₂O]_x with 0 ≤ x ≤ 25 (with a step of 5 mol%), the second one with a constant alkaline oxide concentration of 10 mol%, that is, [TeO₂]_90-y[Ga₂O₃]_y[M₂O]₁₀ with 5 ≤ y ≤ 15 (with step of 2.5 mol%). The values of the glass transition temperature, density, and optical transmission parameters (the positions of short- and long-wavelength absorption edge and the maximum transmittance value) were determined. The changes in these parameters were studied for varying glass compositions. In addition, the values of refractive index were measured at various wavelengths across the whole transparency region reaching from the visible up to the mid-infrared range.

Vitrification of solid technological waste is currently under investigation. For this type of waste made up of metals, minerals, and organic matters, formulation studies were carried out in the NCAS (Na₂O–CaO–Al₂O₃–SiO₂) system in order to define a vitrifying additive to treat the entire waste deposit, while maximizing the waste loading. Main challenge related to this type of waste comes from the presence of alumina in very large quantities in the glass/glass–ceramics melt, enhancing the risk of melt solidification due to a fast and massive crystallization. Melt lock-up can potentially occur at the operating temperature envisaged for the process (1400°C) and is prohibitive because it would lead to a premature stoppage of the process. The results obtained from casting tests, rheological experiments, and thermodynamic modeling enabled to provide an accurate estimation of the risk of melt lock-up for NCAS compositions. It was highlighted that the composition had a major influence on the temperature at which massive crystallization might occur. From all the results obtained, the maximum Al₂O₃ content that could be incorporated in the final material was determined to be close to 50 wt%. The composition of a vitrifying additive was also statistically designed to treat the technological waste of interest.

Next-generation nuclear reactor technologies such as the molten salt reactor utilize alkali metal fluoride salts as both fuel and coolant. In the present study, the suitability of iron phosphate glass (IPG) as a vitrification matrix for alkali metal fluoride (NaF, CaF₂) and simulated fission product loaded fluoride (NdF₃, CeF₃, SmF₃) waste has been explored. The structural change in the metal fluoride–loaded IPG has been analyzed thoroughly using Raman and fourier transform infrared (FTIR) spectroscopy. Thermal analysis showed that the stability and glass forming ability of IPG improved upon loading the same with various mixed metal fluorides. Mössbauer data and X-ray absorption spectroscopy at Fe K-edge explored the minute changes in the local structure. The effect of radiation emanating from radioactive wastes in the fluoride-loaded IPG has been scrutinized via 4.5 MeV proton beam irradiation. Our study firmly establishes the applicability of IPG as suitable vitrification matrix for radioactive metal fluoride–loaded nuclear wastes.

Flexible glass with high bending strength is a remarkable component of flexible electronic displays. However, as a brittle material, its bending properties often do not meet requirements of application. To address this challenge, the application of chemical strengthening stands out as a viable approach to significantly bolster scratch resistance and bending strength in flexible glass. This study focuses on a conventional one-step chemical strengthening method, employing molten potassium nitrate, to reinforce ultrathin aluminosilicate glass produced through the secondary down-drawing thermoforming process. Effects of ion-exchange temperature and time on mechanical properties of strengthened 110 µm flexible glass were investigated, and moreover, properties of strengthened ultrathin flexible glass with various thicknesses were compared. The results indicate that, after chemical strengthening at 380°C for 1 h, the compressive stress (CS) of 110 µm glass reaches 864.60 MPa, and the depth of layer is 15.86 µm, at which time the glass has the best bending performance and scratch resistance, and half of the faceplate spacing during glass breakage can be enhanced from 38.02 ± 2.7 to 8.40 ± 0.62 mm. For ultrathin flexible glass from 40 to 110 µm, after treatment at 380°C for 1 h, the CS of thick glass is higher than that of thin glass, and the enhancement of bending performance is better.