Glass Physics and Chemistry最新文献

The influence of B³⁺ and Pb²⁺ ions on the electrical and mechanical properties of a borate network was extensively studied. A 30B₂O₃–10ZnO–60Na₂O core network was prepared using the commercial melt/quenching technique and inlaid by different concentrations of B₂O₃ + Pb₃O₄ at the expense of Na₂O. The impact of Pb²⁺ and B³⁺ ions on the mechanical properties were studied through ultrasonic wave velocities, elastic moduli, and microhardness. The more bridging oxygens BO₄ that brought to the considered borate network due to the more addition of B₂O₃ and conversion of BO₃ to BO₄ via Pb²⁺ ions penetration, formation of PbO₆, and formation of the strong bonds B–O–Pb reinforced elastic moduli and microhardness of the studied borate network. Electrical properties through dielectric constant, electric modulus, impedance, and ac conductivity were extensively studied. The dielectric constant and electric modulus showed a behavior up to 20 mol % of Pb²⁺ and 35 mol % of B³⁺ differs from after that concentration, while ac conductivity differs at 40 mol % of Pb²⁺ and 50 mol % of B³⁺ from before that concentration. The results of the dependence of conductivity on frequency and temperature showed that the considered glass have a semiconducting nature.

A new method for molecular dynamics (MD) modeling of the glass structure using a crystal structural template is proposed. The template is based on the unit cell of the crystalline phase, whose composition is qualitatively similar to the modeled glass. Using this approach and multistage MD simulation, the model of the spatial structure of grade E borosilicate glass, reproducing its physicochemical characteristics, is obtained. The proposed method enables to model the glass structure using classical MD methods with greater productivity and stability.

A technique for the experimental determination of the thermophysical characteristics of inactive aluminophosphate and borosilicate glasses by differential scanning calorimetry (DSC) is proposed and tested. The advantages of this measurement technique are shown. For glassy matrices of various compositions, the specific heat capacity and thermal conductivity coefficient are determined. The obtained experimental values make it possible to calculate the thermal conductivity values. The applicability of this method is proved by working with real samples of vitrified high-level waste to study their properties and form a database based on them.

In this work an attempt is made to study the impact of the quenching rate upon structure, hyperfine interactions, magnetic and mechanical properties of Fe₇₈Si₉B₁₃ metallic glasses. Other involved parameters in melt spinning method were kept invariant. Analytical techniques comprising X-ray diffraction, transmission Mössbauer spectrometry, vibration sample magnetometer, Vickers microhardness and differential scanning calorimetry were employed. Minor effect of quenching rate upon the macroscopic magnetic properties was detected. It was shown that notable changes in the local atomic arrangement, structure, and mechanical properties were unveiled, dominantly by represent the crystallization at the lowest quenching rate.

Blast furnace slag is produced in large quantities as a by-product in the steel manufacturing process. In this study, a method for synthesizing lead ion adsorbent with high adsorption ability was investigated by alkali activation of the blast furnace slag. A sodium hydroxide aqueous solution was used as an alkali activator, and silica was added to the aqueous solution to improve the adsorption capacity. Alkali activation of the blast furnace slag with the sodium hydroxide aqueous solution yielded lead ion adsorbent. Addition of silica to the sodium hydroxide aqueous solution further increased the lead ion adsorption capacity. Langmuir adsorption isotherms revealed that the highest maximum adsorption capacity of 1658.1 mg-Pb/g was obtained when 5 g of silica was added to 50 mL of the sodium hydroxide aqueous solution. The adsorption capacity for lead ion decreased when more than 10 g of silica was added to the sodium hydroxide aqueous solution.

The article presents the results of a study of new ceramic materials φ-Bi₈Pb₅O₁₇ obtained by pyrolysis using mannitol C₆H₁₄O₆ as a reducing fuel. The values of the band gap of the obtained compositions are determined by analyzing the diffuse reflectance spectra using the Tauc construction. They are in the range from 2.57 to 2.67 eV, which corresponds to visible light photocatalysts. The degree of degradation of methylene orange when using synthesized samples ranged from 95 to 99% when irradiated for 3 h with a fluorescent mercury lamp.

The stability of synthetic and natural zeolites in model biological media simulating the environment of the stomach (pH 1.8), blood plasma (pH 6.9), and intestines (pH 8) is studied. The effect of long-term exposure (up to 7 days) to biological media on the crystal structure of Beta, Rho, Y, and clinoptilolite zeolites is studied. The degree of degradation of the crystal structure of zeolites is controlled by X-ray phase analysis. Based on the results obtained, conclusions are drawn on the prospects for the use of synthetic and natural zeolites as drug carriers.

By using the method of coprecipitation of hydroxides in the ZrO₂–CaO–MgO system, xerogels, powders, and ceramics based on them are obtained. The effect of low temperatures during the preparation of precursors on the phase composition and physicochemical properties of the materials is studied. It is shown that the use of precipitate’s cryotreatment makes it possible to reduce the open porosity and water absorption of the ceramics.

Xerogels and powders of a solid solution based on zirconium dioxide are synthesized by the method of coprecipitation of hydroxides from aqueous solutions of salts of zirconium nitrate ZrO(NO₃)₂⋅2H₂O, aluminum Al(NO₃)₃⋅9H₂O, and cerium Ce(NO₃)₃⋅9H₂O with an aqueous 1 M solution of ammonia NH₄OH. A dense ceramic with low porosity and water absorption is obtained. The effect of the ultrasonic treatment of the precipitate and mechanical treatment of the xerogel on the physicochemical properties of the obtained materials is evaluated.

The dielectric constant (ε'), loss factor (tanδ), and ac conductivity (σ_ac) of 30 Li₂O–10CdO–(60 – x)-B₂O₃:xLn₂O₃, where (x = 0 and 1) and (Ln = Pr, Nd, Sm, and Eu) were investigated using a frequency range of 10²–10⁵ Hz and temperature ranging from 30 to 250°C in this work. The differential scanning calorimetry (DSC) technique was employed to confirm the glassy nature of the materials under study. The dielectric parameters ε', tan δ, and σ_ac rise when rare-earth ions are added to the glass matrix at any frequency or temperature. Dielectric breakdown and activation energies are lower in doped than in undoped glasses while ac current flows through them at room temperature. Rare-earth ion doping’s dielectric parameter values decrease with temperature as atomic number (Z) rises. The dielectric parameter values for the Pr³⁺ doped glass matrix is the highest. QM tunnelling model was used to describe the ac conduction behaviour of these glasses.