Journal of Non-Crystalline Solids: X最新文献

Particles of borophosphate glasses with the nominal molar compositions 16Na₂O-(24-y)CaO-ySrO-xB₂O₃-(60-x)P₂O₅ (mol%), where 0 ≤ x ≤ 60 and y = 0, 12, and 24, were reacted in deionized water and in simulated body fluid (SBF) at 37 °C. For the dissolution experiments in water, the pH of the solution at the conclusion of the experiments increased systematically, from 2.1 to 9.5, for y = 0 glasses when ‘x’ increased from 0 to 60. The reaction rates over the first 8–24 h of dissolution in both SBF and deionized water followed linear kinetics, with reaction rates dependent on glass composition. For glass particles in SBF, replacing P₂O₅ with up to 20 mol% B₂O₃ decreased the dissolution rate (fraction dissolved) by two orders of magnitude, from 7.0 × 10⁻³ h⁻¹ for x = 0 to 2.0 × 10⁻⁵ h⁻¹ for x = 20. Further replacement of P₂O₅ by B₂O₃ increased dissolution rates by three orders of magnitude, to 2.3 × 10⁻² h⁻¹ at x = 60. The compositional dependence of the dissolution rates is explained by changes in the glass structure, with the most durable glasses possessing the greatest fraction of tetrahedral borophosphate sites in the glass network. Crystalline brushite was detected on Ca-glasses with 35 and 40 mol% B₂O₃, but the dominant precipitation phase on both the Ca- and Sr-glasses is an x-ray amorphous material constituted from orthophosphate and pyrophosphate anions.

After assessing compositional dependence of thermal and optical properties of Ge-Ga-Se glasses, we introduce Te, via replacing Se, into Ge₂₅Ga₅Se₇₀ and Ge₃₅Ga₅Se₆₀ (mol%) glasses in an attempt to enhance their refractive index. In the case of Se-deficient Ge₃₅Ga₅Se₆₀ composition, vitrification is achieved for Te content up to 20 mol%. In the case of Se-sufficient Ge₂₅Ga₅Se₇₀ composition, however, formation of bulk glass is realized only when Te content ranges from 25 to 45 mol%. Being proportional to Te content, refractive index of Ge₂₅Ga₅Se₃₀Te₄₀ glass is measured to approach 2.855 at 10 μm, which is far superior to that of any commercialized selenide glasses for infrared-imaging applications. This compositionally tailored Ge₂₅Ga₅Se₃₀Te₄₀ glass is further verified to be compatible with the conventional precision glass molding process, and infrared-imaging performance of the resulting molded lens is as excellent as the existing selenide-glass-based lenses.

Quantitative structure-property relationship (QSPR) is a powerful analytical method to find correlations between the structure of a molecule and its physicochemical properties. The glass transition temperature (T_g) is one of the most reported properties, and its characterisation is critical for tuning the physical properties of materials. In this work, we explore the use of machine learning in the field of QSPR by developing a recurrent neural network (RNN) that relates the chemical structure and the glass transition temperature of molecular glass formers. In addition, we performed a chemical embedding from the last hidden layer of the RNN architecture into an m-dimensional T_g-oriented space. Then, we test the model to predict the glass transition temperature of essential amino acids and peptides. The results are very promising and they can open the door for exploring and designing new materials.

The mechanical behavior of a potassium phospho-aluminosilicate (KPAS) glass which is known to develop near-surface compressive stress profiles resulting from low-temperature water diffusion was explored. Region I of the macro-crack growth curve for the KPAS glass exhibited a steeper slope corresponding to a higher fatigue parameter, n, than soda-lime glass despite a lower n at crosshead speeds of 10⁻¹–10² mm/min and no decrease in strength at lower rates in dynamic fatigue testing. The fatigue limit was easily observed in 50% RH air for the KPAS glass at velocities ~10⁻⁶–10⁻⁷ m/s giving rise to the delayed restart of cracks aged below the fatigue limit. Additionally, a 75% strength increase of the KPAS glass was measured after abraded specimens were aged for 100 days in humid air relative to specimens which were tested immediately following abrasion. The effects of swelling stress, surface stress relaxation, crack healing, and crack tip blunting are discussed.

Perovskite, particularly halide perovskite has drawn increasing attention in recent years because of its remarkable photoelectric properties. However, due to its susceptibility to environmental factors, its research and application have been hampered. Recently, perovskite nanocrystals (PNCs) have been precipitated inside glass by using thermal treatment or femtosecond laser irradiation, which results in unprecedented stability because they are protected by glass matrix. This article reviews the fundamental structure and properties of PNCs, the benefits of perovskite nanocrystals-glass composite structure, and the current state of research into the use of a femtosecond laser to induce PNCs in glass. We also discuss the recent progress in the use of perovskite nanocrystals-glass composite structure for stereo-holographic computing, micro-LEDs and optical storage.