International Journal of Applied Glass Science最新文献

Aluminosilicate glasses present good optical and mechanical properties, but their mechanical behavior can be further improved by thermal or chemical treatments, making them suitable for applications requiring high hardness and fracture strength, for example, laptop monitors or mobile phone screens. A lithium aluminosilicate composition was prepared, and ion exchanged in a KNO₃ bath at different temperatures for various times. Density and UV–vis transmission were measured before and after ion exchange of the glass, together with the mechanical properties, namely, Young's modulus, Poisson's ratio, shear modulus, Vickers hardness, indentation fracture toughness, and equi-biaxial bending strength, whose results were treated by Weibull statistics. The initial glass composition presented a Vickers hardness of 620 ± 10 HV, a Young's modulus of 87 ± 1 GPa, and a fracture toughness of 1.7 ± .1 MPa.m^1/2. After ion exchange, the Vickers hardness of the glass increased to average values of 716 HV for 12 h at 450°C and 728 HV for 30 h at 420°C, while the fracture toughness increased to 2.2 ± .1 MPa.m^1/2, confirming the improvement of the mechanical properties. These results have been compared with two commercial glasses: a monitor glass from a laptop computer and a glass normally used in mobile phone screens.

Reactive classical molecular dynamics simulations of sodium silicate glasses, xNa₂O–(100 − x)SiO₂ (x = 10–30), under quasi-static loading, were performed for the analysis of molecular scale fracture mechanisms. Mechanical properties of the sodium silicate glasses were consistent with experimentally reported values, and the amount of crack propagation varied with reported fracture toughness values. The most crack propagation occurred in NS20 systems (20-mol% Na₂O) compared with the other simulated compositions. Dissipation via two mechanisms, the first through sodium migration as a lower activation energy process and the second through structural rearrangement as a higher activation energy process, was calculated and accounted for the energy that was not stored elastically or associated with the formation of new fracture surfaces. A correlation between crack propagation and energy dissipation was identified, with systems with higher crack propagation exhibiting less energy dissipation. Sodium silicate glass compositions with lower energy dissipation also exhibited the most sodium movement and structural rearrangement within 10 Å of the crack tip during loading. Therefore, high sodium mobility near the crack tip may enable energy dissipation without requiring formation of structural defects. Therefore, the varying mobilities of the network modifiers near crack tips influence the brittleness and the crack growth rate of modified amorphous oxide systems.

Connecting structure with mechanical properties is needed for improving the mechanical reliability of oxide glasses. Although the mechanical properties of silicate and borosilicate glasses have been intensively studied, this is not the case for phosphate and borophosphate glasses. To this end, we here study the structure, density, glass transition, hardness, elasticity, and cracking behavior of lithium borophosphate glasses. The glasses are designed with different B/P ratios to access different boron and phosphorus speciation. The introduction of boron in the phosphate network increases the average network rigidity because of the reduction in the fraction of nonbridging oxygens as well as the exchange of phosphate groups with more constrained BO₄ groups. These structural changes result in an increase in density, Vickers hardness, glass transition temperature, and Young's modulus, and a decrease in Poisson's ratio for higher B₂O₃ content. Furthermore, the increase in network rigidity and atomic packing density results in a lower ability of the glasses to densify upon indentation, resulting in an overall decrease in crack initiation resistance. Finally, we find an increase in the fraction of trigonal boron units in the high-B₂O₃ glasses, which has a significant effect on atomic packing density and Vickers hardness.

A set of in situ measurement equipment of large aperture strong light element based on the principle of laser scattering is established. The size and distribution of defects (damage points) can be judged by the laser scattering signal. The maximum scanning range is 700 mm*1000 mm. The type and size of defects are directly obtained by scanning the quartz sample with a diameter of 100 mm. The types of defects are pitting and scratches, and the width of the scratches and the diameter of the pitting are mostly in the range of 0–10μm. The processing time could reach 31.06s. The device can realize the on-line in situ measurement of large aperture optical elements, and has the advantages of fast response speed and high measurement accuracy.

Thermal treatments of ion-exchanged glasses are often needed for postprocessing steps, including deposition or curing of inorganic or organic coatings deposited on the glass surface. In this study, we investigate the effects of post–ion exchange thermal treatment on the concentration profile, residual stress, and final strength of the ion-exchanged glass. A new general solution of the diffusion problem with variable boundary conditions is presented together with its integration in a recent residual stress model, including fast and slow relaxation terms. Strength is evaluated as a function of the surface flaw depth in both solely ion-exchanged glass and ion-exchanged glass subjected to subsequent thermal treatments. Results indicate that the thermal treatment may have significant detrimental consequences in terms of strength, which should be carefully considered in the design of glass components to avoid unexpected immediate or time-delayed breakages.

A series of Dy³⁺-activated lithium–tungstate–tellurite (LTT) glasses have been synthesized employing a conventional melt quenching procedure. The structural and luminescent features of LTT glasses were examined in detail to reveal their feasibility in solid-state lighting (SSL) applications. Various physical parameters such as density, molar volume, and other parameters were evaluated. A broad hump showed in the X-ray diffraction profile affirms the non-crystalline or amorphous behavior of the as-prepared LTT glasses. The absorption spectrum exhibits several bands between the 400 and 1800 nm range, which confirms that the transitions initiate from the lowest energy state (⁶H_15/2) to numerous excited states. Photoluminescence (PL) spectra reveal three significant peaks centered at 481 (blue), 575 (yellow), and 664 nm (red) related to Dy³⁺ ions under 388 nm excitation. The chromaticity coordinates of LTT glasses were situated in the white light region and nearest to the standard white light (0.33, 0.33). The decay profile shows the biexponential behavior of the prepared LTT (x = 0.1, 1.0, and 2.0 mol%) glasses. Temperature-dependent PL spectra show appreciable thermal constancy of the prepared LTT glasses having a high value of activation energy. The previous results indicate that Dy³⁺-doped tungstate–tellurite glasses are potential luminescent materials to utilize in SSL applications, especially for white light-emitting diodes.

Optical and electrical properties of transparent electrode are directly related to the photoelectric conversion efficiency of thin-film solar cells. For this reason, Ga and Al-doped ZnO (GZO and AZO) transparent conducting films were fabricated on float glass through the magnetic sputtering technique. Compared with AZO films, GZO films show a higher figure of merit (FoM) value indicating their outstanding optical and electrical properties. The smaller difference of ionic radius between Ga³⁺ and Zn²⁺ than Al³⁺ and Zn²⁺ contributes to high carrier concentration and electron mobility of GZO films. In addition, it has been shown that GZO films can be stable at high substrate temperatures. After being annealed at 550°C in N₂ atmosphere, the FoM value of GZO films is twice as much as that of FTO films, indicating that GZO can be applied as the front contact material not only in CIGS thin-film solar cells, but also in CdTe thin-film solar cells.

Sm³⁺-doped and Sm³⁺/Dy³⁺ codoped SiO₂–SrO–MgO glasses were prepared by conventional melt quenching and Sr₂MgSi₂O₇ based glass–ceramics from sintering and crystallization of the glass powders. The thermal, structural, and optical properties of the glasses and glass–ceramics were investigated as a function of the dopant concentration. The optical characterization includes the photoluminescence spectra and the lifetimes of the ⁴G_5/2 (Sm³⁺) and ⁴F_9/2 (Dy³⁺) excited states. In Sm³⁺ single-doped samples, the emission intensity increases up to a concentration of 0.3 mol% Sm³⁺ ions and then decreases due to nonradiative energy transfer processes. The emission spectra in the glass–ceramics show a more resolved structure and higher intensity compared to the glass samples, suggesting a different and crystalline environment for the Sm³⁺ ions. The non-radiative processes also influence the experimental decays of the glass samples which deviate from a single exponential with lifetimes decreasing as Sm³⁺ concentration increases. The emission and excitation spectra of the codoped samples do not show significant energy transfer between Sm³⁺ and Dy³⁺ ions. Different emitting colors can be obtained in the codoped glasses by changing the excitation wavelength. The studied glass–ceramics could be applied as enamels on ceramic or metallic substrates.

Nanoscale composition fluctuations in Li₂O–SiO₂-based glasses were analyzed and discussed from the data on the structure and crystallization process reported so far to enter deeply into the medium-range ordered structure of multicomponent oxide glasses. Li₂O is proposed to have a strong tendency for dynamical heterogeneous structure, that is, the formation of fragile Li₂O-rich regions with small SiO₂ contents, resulting in the initial crystallization of metastable Li₂SiO₃ prior to the formation of stable Li₂Si₂O₅ in Li₂O–2SiO₂-based glasses. Li₂O–Ga₂O₃/Nb₂O₅–SiO₂ glasses are proposed to have nanoscale composition fluctuations of Li₂O–Ga₂O₃/Nb₂O₅-rich regions, resulting in the initial formation of LiGa₅O₈ and LiNbO₃ nanocrystals. In Li₂O–Al₂O₃–SiO₂ glasses, the distribution width of composition fluctuations is proposed to be narrow, resulting in the initial crystallization of metastable β-quartz solid solutions Li₂O·Al₂O₃·nSiO₂ (n = 6–8). Additive P₂O₅ and NiO leading to an enhanced nucleation are proposed to be present in fragile Li₂O-rich regions.

A comprehensive study of the batch-to-melt (BtM) conversion process was carried out on a single high-boron alkaline earth aluminosilicate glass composition, which is relevant to manufacturing high-performance fiberglass for high-end electronic applications. In the study, we used several techniques to trace the BtM process from room temperature up to 1400°C, namely isotherm batch heat-treatment, X-ray diffraction (XRD), hot-stage microscopy (HSM), high-temperature differential scanning calorimetry (DSC), and Fourier transform infrared (FT-IR). In the BtM process, the intermediate aluminum borate phase (Al₄B₂O₉) between 1000 and 1100°C was identified. The formation of Al₄B₂O₉ is explained in conjunction with the dihydroxylation of kaolin. For the first time, the potential use of the FT-IR method in studying the BtM process was demonstrated, including the dissolution of sand above 1100°C.