Glass and Ceramics最新文献

In this work, a titanium oxide-modified silicon oxycarbide composite was synthesized. A combined mechanical treatment by deposition of TiO₂ on the surface of white soot and activated carbon was used. The fixation of titanium oxide was confirmed by elemental analysis data. Scanning electron microscopy (SEM) showed that the size of the deposited particles did not exceed 100 nm. The structure of the obtained materials was studied by x-ray diffraction and IR spectroscopy. It was shown that the silicon oxycarbide composite has a high degree of amorphism; the diffraction pattern contains peaks characteristic of reflections from anatase planes. The IR spectra contain bands corresponding to vibrations of the Ti–O–Ti and Ti–O–C bonds. The porosity of the synthesized samples was investigated by low temperature nitrogen adsorption/desorption. It was found that the composite has a sufficiently developed porous structure with a predominance of meso- and macro pores. The material is proposed to be used as a photocatalyst for the degradation of organic compounds in cleaning processes.

A cubic pyrochlore with the composition Bi₂Ni_1/2Co_1/2Ta₂O_9±δ (sp. gr. Fd–3m, a = 10.5261(8) Å) was synthesized from the corresponding oxides by the solid phase reaction method for the first time. The complex oxide is characterized by a porous microstructure formed by partially fused crystallites of elongated shape with an average longitudinal size of 1 – 2 μm. The chemical state of the transition element cations in pyrochlore was characterized by x-ray photoelectron spectroscopy (XPS) and x-ray absorption near edge structure (NEXAFS). A characteristic shift of the Ta4f spectrum by 0.8 eV into the low energy region is observed for the pyrochlore. The charge state of the tantalum cations corresponds to a value of +(5 – δ). The absorption spectrum of pyrochlore near the Co2p absorption edge is a superposition of the CoO and Co₃O₄ spectra. According to the nature of the XPS, and NEXAFS Ni2p spectra the nickel ions are in the Ni(II, III) state.

This paper analyzes composite materials based on K 25 hollow glass microspheres modified with silver nanoparticles (Ag NPs). The nanoparticles were produced by an eco-friendly green method using an aqueous plant extract from Taraxacum root as a reducing agent. The synthesis of the nanoparticles and their deposition on the surface and within the pores of the microspheres were achieved simultaneously through ultrasonic treatment, followed by thermal processing at 300 – 350°C. The developed composites, consisting of K 25 hollow glass microspheres with supported silver nanoparticles, were characterized using scanning electron microscopy (SEM), infrared (IR) spectroscopy, and x-ray diffraction (XRD). The elemental composition was determined by energy-dispersive x-ray spectroscopy (EDS). The results demonstrate the effectiveness of the proposed method for depositing silver nanoparticles onto the surface of glass microspheres.

This study investigates the morphology of nickel and cobalt oxides deposited on various substrates, specifically γ-alumina and silica gel. The primary objective of this study was to examine the influence of synthesis methods, such as impregnation and mechanochemical synthesis, on the textural properties and surface morphology of the resulting composites. We employed scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and low-temperature nitrogen adsorption/desorption (the Brunauer–Emmett–Teller (BET) method) to analyze the characteristics of the composites. The findings of the study demonstrated that the synthesis method significantly affects the particle size and shape of the oxides, as well as the distribution of nickel and cobalt oxides on the substrate surfaces. Although the impregnation method ensures a uniform distribution of metal oxide particles, they exhibit a higher tendency for agglomeration, particularly in the case of cobalt oxide. The mechanochemical method enhances the mobility of components and improves adhesion, resulting in a higher dispersion of the metal oxides. This is achieved through controlled encapsulation of the oxides within the substrate. The findings may facilitate the development of novel composite materials with improved catalytic and structural properties.

Ceramics in the Ca₂P₂O₇–Ca₃(PO₄)₂ system were obtained from powder mixtures containing calcium hydroxyapatite Ca₁₀(PO₄)₆(OH)₂ and monocalcium phosphate monohydrate Ca(H₂PO₄)₂· H₂O. Fish scale powder was used as a natural source of natural calcium hydroxyapatite Ca₁₀(PO₄)₆(OH)₂. The molar ratios of Ca₁₀(PO₄)₆(OH)₂ /Ca(H₂PO₄)₂· H₂O in the initial powder mixture equal to 1/4, 3/5 and 2/1, respectively, ensured the formation after firing of ceramics having a desirable phase composition, including calcium pyrophosphate Ca₂P₂O₇ and/or tricalcium phosphate Ca₃(PO₄)₂ . The homogenization of the components was carried out by repeated passing of the powder mixture through a sieve with a mesh size of 200 μm. Plastic molding of the samples was carried out using ethyl alcohol as a binder. According to XRD data, the phase composition of all samples after the addition of alcohol, molding, and drying included monocalcium phosphate monohydrate Ca(H₂PO₄)₂· H₂O and calcium hydroxyapatite Ca₁₀(PO₄)₆(OH)₂. Monetite CaHPO₄ and brushite CaHPO₄· 2H₂O were also present in the phase composition of the samples. The phase composition of prepared highly porous ceramic samples with relative density 27 – 55% after firing in a temperature range of 900 – 1100°C included β-tricalcium phosphate β–Ca₃(PO₄)₂ and/or β-calcium pyrophosphate β–Ca₂P₂O₇.

The results of experimental modeling of glassy carbon production from high-pressure supercritical fluid (SCF) in the C–O–H system at a temperature of 800°C and pressures of 500 – 1000 atm are presented. Acomprehensive characterization of the carbon material is presented, using the data from CHNS-O analysis, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), x-ray and electron diffraction, infrared and multiwavelength Raman spectroscopy (Raman). In light of the characteristics and outcomes of the comparison with industrial glassy carbon, the synthesized carbon material was classified as a glassy substance. The findings of the experimental studies provide evidence for potentially different mechanisms of formation and, consequently, polygenicity of the glassy state of carbon. The material obtained through a radically distinct production method (polycondensation) may possess distinctive surface and bulk properties.

The preparation of copper green glaze was conducted using a combination of raw materials, including kaolin, feldspar, calcite, talc, limestone, quartz, and copper oxide. The influence of formulation composition and preparation process on the surface of green glaze was examined through the application of single-factor and orthogonal experimental design methodologies. The single factor experimental method entailed a systematic alteration of a single factor, such as the proportion of raw materials, firing temperature, or firing time, to examine its individual impact on the surface of the green glaze. In contrast, an orthogonal experimental design simultaneously considers multiple factors and assesses their relative importance for the glaze effect. The objective of this study is to optimize the formulation composition and preparation process of copper green glaze in order to achieve the desired surface effect and to improve the efficiency and quality of glazes in industrial manufacturing applications.

A methodology for the analytical calculation of the glass thermal conductivity coefficient is proposed. This methodology allows for the reliable calculation of thermal conductivity coefficients for glass products of varying thicknesses, taking into account the physical essence of the radiation-conductive heat transfer process in semitransparent media. Furthermore, this methodology facilitates the analysis of temperature conditions during glass melting and the operation of glass products.

Bi₂Zn_xMn_1–xTa₂O_9.5–∆ ceramics were synthesized for the first time using the solid phase synthesis method. The samples were found to contain cubic pyrochlore (sp. gr. Fd–3m) as the main phase and a triclinic modification (sp. gr. P-1) of BiTaO₄ as admixture. The amount of the triclinic modification is proportional to the manganese content in the samples. The formation of impurities is associated with the distribution of a fraction of the transition element ions into the cationic sublattice of bismuth (III). The unit cell parameter of the pyrochlore phase increases with increasing content of zinc ions in the samples from 10.4895(5) Å (x = 0.3) to 10.5325(5) Å (x = 0.7) in accordance with the Vegard rule. The formation of impurities in samples can be prevented by creating a bismuth ion deficiency in the bismuth sublattice by an amount proportional to the β-BiTaO₄ content. The unit cell parameter of single-phase pyrochlores Bi_2–yZn_xMn_1–xTa₂O_9.5–∆ synthesized in this way increases with increasing zinc ion content in the samples from 10.4764(5) Å (x = 0.3) to 10.5122(5) Å (x = 0.7). As observed through electron scanning microscopy, the ceramic samples exhibit a low-porosity microstructure with indistinct grain boundary outlines. The porosity of the samples decreases as the zinc content of the samples increases. The formation of a deficient bismuth sublattice during preparation is associated with a more porous microstructure, which can be attributed to a reduced concentration of the readily fusible component present in the reaction mixture, namely bismuth (III) oxide.

α–Al₂O₃–3YSZ porous ceramics were fabricated using the slip casting method with the incorporation of 15 wt% of submicron Al₂O₃ powders as sintering additives. The materials were prepared by solution combustion synthesis using glycine or urea as fuels. Following firing of the ceramics at 1550°C, the percentage of closed porosity was found to be in the range from 14.1 to 24.0%. The experimental results revealed a linear correlation between density and closed porosity of Al₂O₃–3YSZ corundum ceramics. Ceramic samples that underwent firing at 1550°C exhibited relative density values ranging from 75 to 85%, accompanied by an open porosity of 0.90 to 1.71%. The findings indicate that the morphology of the used aluminum oxide additives synthesized through combustion exerts a predominant influence on the strength characteristics.