Glass Physics and Chemistry最新文献

Researchers investigated into how thickness and quenching temperature affect the mechanical and thermomechanical properties of titanium dioxide-pigmented polycarbonate. By using compression molding, specimens free of morphological effects have been generated. Dynamic mechanical analysis was used to evaluate plates with thicknesses of 0.6, 1, 2, and 3 mm under flexion, Izod impact strength, density, and tensile testing. Two distinct heat treatments annealing and second quenching were applied. The results indicate that a second quenching at 40°C for samples 3 mm thick and 35°C for samples 2 mm thick can enhance the impact strength and elongation at break, and a relationship between the mechanical, physical, and thermomechanical properties is detected. At the expense of other characteristics like elastic modulus, density, and yield stress, these properties are improved. A relaxation mode about 30°C is associated with improved impact strength and elongation at break following the second quench.

In this research, the process is presented to remove the solubility of raw materials in water instead of frittic process. Therefore a suitable glaze for single fast firing floor tile consisted of 80 wt % raw glaze and 20 wt % frit was considered. An initial batch of frittic glaze including silicate, calcite, soda, and acid boric becomes a low soluble compound first by melting and quenching in water (frittic process) and also by firing at different temperatures that firing causes the formation of low solubility phase. Then these glazes mixed with 80 wt % raw glaze. Glazes slip applied on the dried floor tile bodies and then fired in fast firing kiln. Properties of glazes (thermal expansion coefficient, T_g, micro-hardness) were compared. Also by X-ray diffraction analysis and solubility analysis proved low soluble phases formed in glaze by firing initial batch of frit at 800°C.

Synthesis of precursor powders was performed by microreactor technique in a two-step microreactor with intensively swirled reagent flows. Ceramic samples (matrices) (1 – х)ZrSiO₄‒хZrO₂ were obtained by sintering nano-sized precursor powders in the 1000–1300°C temperature range in air. X-ray phase analysis has shown that at a temperature of 1300°C, partial decomposition of zircon was observed with the formation of a silicon oxide. Their thermal behavior was studied by dilatometry, and the temperature coefficient of linear expansion was accessed. The chemical stability of the obtained ceramic matrices was evaluated by the method of prolonged leaching in distilled water, more precisely, by the release into the contact liquid of both matrix components (Zr, Si) and specially introduced radionuclides (¹³⁷Cs, ⁹⁰Sr, ¹⁵²Eu). The samples exhibited sufficiently high chemical stability, which allows us to consider them as a possible matrix material for immobilization of high-level waste.

Using computer methods (the ToposPro software package), a combinatorial-topological analysis and modeling of the self-assembly of Li₂₈Cu₄Si₈-oP40 (a = 7.969 Å, b = 4.449 Å, c = 17.244 Å, V = 611.46 ų), La₁₂Rh₁₂Al₁₆-oP40 (a = 26.949Å, b = 4.218Å, c = 7.267 Å, V = 826.05 ų), and Ca₈Pt₁₂Sn₂₀-oP40 (a = 27.701 Å, b = 4.614 Å, c = 9.371 Å, V = 1198.02 ų) crystalline structures with the Pnma space group are carried out. For Li₂₈Cu₄Si₈-oP40, the self-assembly of the crystal structure with the participation of supraclusters-trimers from K6(4a) = 0@6(Li₄Cu₂) clusters, two clusters K6(8d) = 0@6 (CuLi₅), and Si spacer atoms is considered. For La₁₂Rh₁₂Al₁₆-oP40, the self-assemblies of the crystal structure with the participation of K3(8d) = 0@3(LaRhAl) clusters and K6(4a) = 0@6(La₂Rh₂Al₂) clusters from the linked LaRhAl clusters and K4(8d) = 0@4(LaRhAl₂) clusters are considered. For Ca₈Pt₁₂Sn₂₀-oP40, the self-assembly of the crystal structure from clusters-precursors in the form of the K6 = 0@6(CaSn₃Pt₂) double tetrahedra and K4 = 0@4(CaSn₂Pt) tetrahedra is considered. The symmetry and topological code of the processes of the self-assembly of Li₂₈Cu₄Si₈-oP40, La₁₂Rh₁₂Al₁₆-oP40, and Ca₈Pt₁₂Sn₂₀-oP40 from K3, K4, and K6 clusters-precursors are reconstructed in the following form: primary chain → layer → framework.

It is established that the ZnO–Al₂O₃ oxide coating formed on the surface of aluminosilicate fibers contains hexagonal 13-nm ZnO crystals. The obtained composites demonstrate intense generation of singlet oxygen under the influence of UV radiation. Increasing the radiation power density provided a significant increase (+60%) in the intensity of singlet oxygen generation. It is established that the application of an oxide coating significantly accelerates the processes of adsorption of the aniline blue organic dye from aqueous solutions on the surface of fibers and its photocatalytic decomposition under the influence of near-UV radiation. The kinetics of the dye adsorption process are clearly described by a pseudo-second-order kinetic equation. The application of an oxide coating on the surface of the fibers significantly accelerates the photolysis processes of the dye in the solution. The photolytic decomposition rate of the dye in solution is described by a pseudo-second-order kinetic equation.

Xerogel in the ZrO₂–Y₂O₃ system s are obtained by using the traditional method of coprecipitation of hydroxides and in a microreactor with countercurrent intensely swirling flows of reagents. Their physical and chemical properties are studied. The patterns of influence of the synthesis method on the phase composition of powders and ceramics based on zirconium dioxide are revealed. Ceramic materials with high strength characteristics, consisting of a mixture of cubic and tetragonal modifications of ZrO₂ are obtained.

Using computer methods (the ToposPro software package), combinatorial-topological analysis and modeling of the self-assembly of Y₈Rh₁₂Sn₂₀-oS40 (a = 4.387 Å, b = 26.212 Å, c = 7.155Å, V = 822.77 ų), Lu₁₆Zn₂₀Ge₂₄-oS60 (a = 4.179 Å, b = 18.368 Å, c = 15.050 Å, V = 1155.24 ų), and Ba₈Ir₁₆In₅₂-oS76 (a = 4.485 Å, b = 29.052 Å, c = 13.687 Å, V = 1783.63 ų) crystal structures with the Cmc2₁(36) space group are carried out. For Y₈Rh₁₂Sn₂₀-oS40, 18 variants for identifying cluster structures with the number of clusters N = 1 (variant 1), 2 (variant 11), and 3 (6 variants) are established. The variant of the self-assembly of a crystal structure with the participation of clusters-precursors forming the packing in the form of the K6 = 0@6(YSn₃Rh₂) and tetrahedra K4 = 0@4(YSn₂Rh) double tetrahedra is considered. For Lu₁₆Zn₂₀Ge₂₄-oS60, 66 variants are established for identifying cluster structures with the number of clusters N = 1 (1 variant), 2 (25 variants), 3 (20 variants), and 4 (20 variants). The variant of the self-assembly of a crystal structure with the participation of K3(D1) = 0@3(Lu Ge₂), K3(D2) = 0@3(Lu Zn Ge), K3(D3) = 0@3(Lu Zn Ge), K3(D4) = 0@3Lu Zn Ge), and K3(D5) = 0@3(GeZn₂) 3-atom clusters-precursors forming the packing is considered. For Ba₈Ir₁₆In₅₂-oS76, 129 variants are established of the allocation of cluster structures with the number of clusters N = 2 (36 variants) and N = 3 (103 variants). The variant of the self-assembly of a crystal structure with the participation of the clusters-precursors forming the packing is considered: K6 = 0@6(BaIn5) pentagonal pyramids, K4a = 0@4(BaRhIn2) tetrahedra and K4b = 0@4(Rh₂In2) tetrahedra, K3 = 0@4(RhIn₂) rings, and In spacer atoms. The symmetry and topological code of the self-assembly processes of the Y₈Rh₁₂Sn₂₀-oS40, Lu₁₆Zn₂₀Ge₂₄-oS60, and Ba₈Ir₁₆In₅₂-oS76 crystal structure from K3, K4, and K6 clusters-precursors in the following form is reconstructed: primary chain → layer → framework.

In this paper, we studied the Na₂O–CaO–B₂O₃–TeO₂–Sm₂O₃ (labeled as NCBT-Sm) for the physical, optical, and luminescence properties of the NCBT-Sm glasses. The XRD study confirmed the amorphous nature of the glass. The density and molar volume increase with increasing concentration of TeO₂. We found four emission peaks located at 562, 597, 644 and 706 nm corresponding to ⁴G_5/2 → ⁶H_5/2, ⁴G_5/2 → ⁶H_7/2, ⁴G_5/2 → ⁶H_9/2 and ⁴G_5/2 → ⁶H_{1 1/2} transitions respectively. The emission and absorption spectra were analyzed using the Judd–Ofelt theory to calculate various spectroscopic parameters, such as emission cross-section, radiative transition probability, branching ratios, and stimulated emission cross-section. The color coordinates of all the glass samples lie in the orange region of the Commission International de l’Eclairage (CIE) diagram. The results obtained in the present work show that these glasses may be a potential candidate for LED applications.

A two-layer superhydrophobic coating consisting of a heating and water-repellent layer is obtained. The heating layer, which is a percolation network of carbon nanotubes (CNTs), is reinforced with a polymer to improve surface adhesion, strength, and wear resistance. Epoxy resin is used as a reinforcing polymer. Various methods of organizing a heating layer from CNTs with a reinforcing polymer are considered, and the best ones are identified for creating a heating or antistatic surface. The influence of the concentration of CNTs in the polymer on the strength of the composite is studied. Different methods of introducing nanotubes in the polymer are compared to achieve the best deagglomeration of nanoparticles. The effects of functionalization of nanotubes are tested, and an increase in the coating strength with a slight increase in conductivity is revealed. The optimal concentration of Taunit-M carbon nanoparticles for strengthening ED-20 epoxy resin is found to be 0.07% for nonfunctionalized nanotubes and 0.5–0.6% for particles with –CONH₂ in groups. It is possible to achieve a superhydrophobic state of the surface: the contact angle of wetting is 152.3 ± 0.7 and the angle of the beginning of the sliding of the droplet is 1.6 ± 0.9.

Indian nuclear industries emphasize on metal fuel which shows significant advantages over ceramic fuels in fast reactor fuel cycles, where sodium is used as bonding material. The sodium discharged from rejected sodium bonded metal fuel pins is blended with uranium and plutonium metals labelled as contaminated sodium. This contaminated sodium is converted to borosilicate glass with the addition of suitable glass formers and modifiers. Pristine borosilicate glass of known composition and doped glasses were prepared with fixed Na/Si ratio by addition of (i) U₃O₈ (5 wt %) and (ii) oxides of U, Ce, Nd, and Gd (together 5 wt %) labelled as BSGU and BSGURE respectively. Thermo-physical properties of these glasses are favourable towards safe disposal however, it is essential to evaluate aqueous alteration named as chemical durability (at 363 K) before using contaminated sodium. Surface morphology and chemical durability of pristine BSG were evaluated and compared with doped BSGs. The normalized leach rate for seven days was found to be 1.8 × 10^–4, 5.5 × 10^–5, and 4.2 × 10^–5 g cm^–2 day^–1 for pristine BSG, BSGU, and BSGURE respectively. The enhancement of chemical durability on doped glasses is due to addition of dopants.