Glass and Ceramics最新文献

We synthesized nanoporous ceramic materials using yttrium oxide (Y₂O₃) characterized by a cubic crystal structure, which is resistant to sintering. The synthesized materials included composites containing approximately 10 wt.% α-Al₂O₃. The pore structure and filtration characteristics of the resulting ceramics were examined. The materials were tested in aggressive environments, including 20 wt.% H₂SO₄ and 10 wt.% KOH aqueous solutions, and under thermal cycling. The results showed no deformation or degradation in corrosive media, and thermal cycling led to no deterioration of the physical or mechanical properties. Filtration tests using model SiC particle suspensions (D₅₀ = 500 nm) demonstrated a rejection efficiency exceeding 99.9%. The combination of favorable performance characteristics and a well-developed porous structure makes these materials suitable for the micro- and ultrafiltration of liquids and for catalytic processes under aggressive media and high thermal loads.

This study investigates the effect of the formation temperature of an adhesion contact on the interfacial strength in (Ge₂₁Te₇₉)_100–x(AgI)_x glass–quartz glass systems. The contact wetting angles of (Ge₂₁Te₇₉)_100–x(AgI)_x glass melts on a quartz glass substrate were determined experimentally, and the surface tension of these chalcogenide glasses was measured. The temperature dependence of the work of adhesion for the (Ge₂₁Te₇₉)_100–x(AgI)_x glass melts to quartz glass was also examined. The findings indicate a correlation between the adhesive strength of the solid-phase boundary and the work of adhesion of the chalcogenide melt to the quartz glass surface. The adhesive strength of the (Ge₂₁Te₇₉)_100–x (AgI)_x glasses to quartz glass increases from 508 to 1104 kPa as the silver iodide content rises from 30 to 50 mol.%.

This study investigates the physicochemical characteristics and phase transformations of diabase rocks from the Uzunbulak deposit, Uzbekistan. The results demonstrate that firing at 1000°C induces phase transformations in the diabase samples, leading to the formation of wollastonite, pyroxene, and minor amounts of high-temperature quartz and cristobalite. The feasibility of using this diabase rock as a raw material component for producing acid-resistant materials with various applications has been established.

Chromium-containing solid solutions CaCu₃Ti_{4 – 4x}Cr_4xO_12–δ (space group Im3) were synthesized by the solid-state method. The unit cell parameters vary slightly, from 7.3897 Å (x = 0.02) to 7.3866 Å (x = 0.06). Copper oxide is detected in the intergranular space of all samples. The ceramics exhibit a low-porosity grain microstructure. Scanning electron microscopy (SEM) indicates that an increase in the chromium content (x = 0.01 – 0.06) leads to a reduction in the maximum longitudinal crystallite size from 16 to 10 μm. The charge states of cations in chromium-doped calcium copper titanate CaCu₃Ti₄O₁₂ (CCTO) were investigated using x-ray photoelectron spectroscopy (XPS) and near-edge x-ray absorption fine structure spectroscopy (NEXAFS). Spectroscopic data confirm that titanium cations exhibit a +(4 – δ) charge state, while copper and calcium cations are in the +2 state and chromium cations in the +3 state.

This study investigates the chemical and mineralogical composition, particle size distribution, and physical and chemical properties of raw dune sands from the Kushkupyr district of Uzbekistan. The particle size distribution indicates a predominance of particles larger than 0.007 mm, with a fineness modulus of less than one, which classifies these sands as fine-grained. Scanning electron microscopy (SEM) reveals that the sand particles consist primarily of irregularly shaped quartz grains. This work proposes compositions for producing sodium silicate based on a microsilica – dune sand – caustic soda system.

The study examines the effect of varying yttria (Y₂O₃) content, used as a stabilizing dopant, on the micro-structure, phase composition, and mechanical properties of zirconia (ZrO₂)-based ceramics fabricated by electron-beam sintering under forevacuum conditions. Samples with Y₂O₃ concentrations ranging from 1.8 to 31.5 wt.% were investigated. An increase in the proportion of yttria in the initial mixture resulted in a decrease in the density of the sintered ceramics, while simultaneously promoting the stabilization of the tetragonal ZrO₂ phase. This phase stabilization enhanced the strength characteristics of the material, even in the absence of applied pressure during sintering. The highest microhardness, reaching 5.64 GPa, was achieved at a concentration of 15 wt.% Y₂O₃.

A ceramic composite was synthesized using β-CaSiO₃ (wollastonite) with perovskite additives and an Al₂O₃–CuO–Li₂CO₃ sintering aid. This study examines the influence of sintering additives on the ceramic and dielectric properties of both CaSiO₃/Al₂O₃–CuO–Li₂CO₃ and CaSiO₃/CaTiO₃–Al₂O₃–CuO–Li₂CO₃ systems. The thermal conductivity λ of the obtained samples ranged from 0.43 to 0.65 W/(m ∙ K), which is characteristic of wollastonite ceramics. The relative dielectric permittivity ε_r ranged from 4.9 to 8.0, the dielectric loss tangent (tan δ) was (15.3–17.9) × 10 ^–3 at a frequency f of 1 MHz, and the average density ρ_av was 2.44 – 2.63 g/cm³. Sintering was carried out at temperatures ranging from 875 to 950°C. The combination of these properties, along with low thermal conductivity λ, meets the criteria for thermally stable ceramic packages and substrates used in low-temperature co-fired ceramic (LTCC) microelectronics applications.

In this work, we set out to develop a laser-induced breakdown spectroscopy (LIBS) method for monitoring the homogeneity of optical glasses in terms of chemical composition. A quantitative LIBS-based method for studying lead distribution over the surface area of lead silicate glasses is proposed. The parameters of laser radiation acting on the surface of lead silicate glasses (pulse energy, laser pulse repetition rate, laser wavelength, delay between the pulse and the analytical signal registration) are optimized. The minimum step of scanning the chemical composition over the surface area of a sample was established to be 300 μm.

The restoration of natural ecosystems is among the most urgent contemporary challenges, demanding prompt and effective solutions. In light of severe and widespread environmental pollution, active remediation efforts have become imperative. One of the most promising strategies for recycling drilling waste involves its conversion into value-added materials, such as proppants, ceramics derived from drill cuttings (shlamolite), and ceramic stones (keramsten). Beyond improving waste management, repurposing drill cuttings as a raw material could reduce industrial demand for virgin natural resources. This paper presents the physical and chemical analyses of drilling waste and evaluates its potential for the synthesis of high-performance aluminosilicate materials.

This study examines the spectral and luminescent properties of zinc phosphate glasses in the ZnO–P₂O₅ (PZ) system, doped with 0.25 – 1.00 mol.% Er₂O₃. An increase in the Er₂O₃ content results in an intensification of the luminescence band centered at approximately 1537 nm. We evaluated the phenomenological Judd–Ofelt intensity parameters (Ω_t, where t = 2, 4, 6) and calculated the corresponding radiative transition probabilities, branching ratios, stimulated emission cross sections, and radiative lifetimes of the excited state. The obtained results demonstrate the potential of the studied material as an active medium for near-infrared (NIR) emission.