Porous ceramic materials based on a coarse Al2O3 filler were synthesized using fine MgO, SiO2, and SiC binders by compaction at pressures of 20…40 MPa followed by sintering in the temperature range of 1100…1300 °C. It was established that at 1100 °C a weakly consolidated structure is formed, whereas at 1200 °C and above liquid-phase sintering occurs, leading to strengthening of the ceramic framework. The formation of the pore structure is completed at 1300 °C. An increase in the sintering temperature from 1100 to 1300 °C results in more than a threefold increase in flexural strength, while an increase in the compaction pressure from 20 to 40 MPa provides a twofold strengthening effect while maintaining high porosity, gas permeability, and structural homogeneity. The obtained results demonstrate the possibility of targeted control of the structural and functional properties of porous ceramics through optimization of synthesis parameters. This work shows potential for the cost-effective production of Al2O3-based membranes for microfiltration processes, as well as catalyst supports for operation under aggressive environments and high thermal loads.
This article presents a comprehensive study of thin-film coatings based on indium tin oxide. The percolation threshold is established at ?6.8 nm, above which a continuous electrically conductive film is formed. A systematic analysis is performed of the evolution of microstructural and optoelectronic properties across the percolation transition, both in the as-deposited amorphous state and after thermal annealing at 400 oC. The optical band gap, determined within the indirect-transition model, is found to exhibit a non-monotonic dependence on film thickness in the vicinity of the percolation threshold. A correlation between morphology and wettability is revealed, manifesting as an abrupt change in the water contact angle across the percolation transition. It is shown that recrystallization induced by annealing does not shift the percolation threshold; however, it significantly enhances the crystalline quality and reduces the surface defect density, as confirmed by X-ray diffraction and transmission electron microscopy data. The obtained results provide a foundation for the targeted design of ultrathin ceramic coatings with predictable optoelectronic and microstructural properties.
Inorganic glass scintillators are an important class of materials for detecting ionizing radiation in medicine, nuclear power, high-energy physics, and security systems. Despite their lower light yield compared to single crystals, they offer advantages: ease of manufacturing complex shapes, low cost, high radiation resistance, and the ability to uniformly dope with activators. This review systematizes current understanding of the compositions, properties, and limitations of glass scintillators, a key one being luminescence quenching. Intrinsic (OH? groups, concentration quenching, structural heterogeneity) and extrinsic (temperature, radiation) factors that reduce efficiency are analyzed. This review examines promising matrices (silicate, phosphate, borate, and oxyfluoride), the role of rare earth ions (Ce3+, Tb3+, Eu3+, Gd3+), and new approaches such as microwave synthesis, 3D printing, and computational methods. This review summarizes achievements and identifies paths to creating highly efficient glass scintillators.
The process of femtosecond laser welding of lithium aluminosilicate glass ceramics was studied. The influence of laser pulse energy (1…10 µJ), scanning speed, and focusing depth on the geometrical characteristics and structural changes in the material was investigated. Using optical and scanning electron microscopy as well as Raman spectroscopy, it was shown that exposure to pulses with an energy of 2 µJ and above induces local amorphization of the glass ceramic structure. It was found that an increase in energy leads to an increase in the weld height from 130 to 240 µm, while variations in scanning speed within the studied range do not have a significant effect. Shear strength tests were carried out on welded joints made with circular and spiral trajectories. It was demonstrated that the use of a spiral trajectory allows the average joint strength to be increased almost threefold (up to 19.5 MPa) compared to the circular trajectory (7 MPa). The obtained results show the promise of using a spiral trajectory for creating reliable welded joints of glass ceramics.
The approaches to laser processing of ultra-thin K-208 glass, which is promising for the fabrication of glass interposers in 2.5D/3D microelectronics, are considered. The requirements for through-glass vias (TGV) and cut quality, including geometry, aspect ratio, and uniformity of metallization, are discussed. The feasibility of two laser methods was studied: drilling using sub-nanosecond bursts of femtosecond pulses and cutting by controlled thermal cleavage using a CO2 laser. In the experiments, the energy and number of pulse bursts, the beam waist position, as well as the CO2 laser parameters and the number of passes, were varied. The morphology of the holes and cuts was analyzed by optical microscopy. Stressed regions and the bending strength of the samples were studied. The fundamental possibility of forming through holes in ultra-thin glass ribbon and obtaining a defect-free laser cut was demonstrated. Factors limiting reproducibility and strength were noted, and the role of subsequent heat treatment was assessed. The obtained data can be used in the development of technological processes for manufacturing glass interposers.
Impact glasses are naturally occurring amorphous materials formed by high-velocity meteorite impacts on the Earth's surface. This paper examines the structural features of a high-pressure variety of impact glasses from the Kara astrobleme. The nanostructural characteristics of the shock glasses in the 1…100 nm range were studied using small-angle X-ray scattering (SAXS) of synchrotron radiation. The results demonstrate a bimodal distribution of nanoscale inhomogeneities. Large inhomogeneities (~60 nm) are interpreted as Fe- and Ti-rich nanoclusters formed as a result of liquation phase separation or partial crystallization of the melt. Small inhomogeneities (~10 nm) are identified as pores resulting from melt degassing during rapid decompression. Analysis of the SAXS curves using the Beaucage model revealed a hierarchical organization of the material: elementary building blocks (Rsub ? 4.7 nm) form nanoclusters with a mass fractal dimension Dm = 2.6, which in turn form large aggregates (Rg > 150 nm). The pore surface is characterized by a fractal dimension Ds = 2.82, indicating their roughness and non-equilibrium formation conditions.
Due to the lack of literature data on the strength of heterogeneous laminated glass with electric heating elements, this study utilized the centrosymmetric bending method to investigate the ultimate strength of these composites. Based on these experimental studies, we obtained data on the strength properties of the heterogeneous composites. Based on these results, we concluded that the method of forming the electric heating element on the glass surface does not significantly affect the composites' strength characteristics.
To obtain Al–Al2O3 cermet with a heterogeneous granular-layered structure, aluminum powder of the industrial grade PAP-2 with a flaky particle shape and plasma-chemical alumina powder (PCAP), consisting of lamellar agglomerates (LLC “Kit-Stroy SPb”), were used. The PAP-2 and PCAP powders were mixed, the resulting mixture was briquetted, the briquette was mechanically ground, billets from the resulting dispersed product were pressed, after that billets were heat treated in a vacuum (630 °C, 1 h), calibrated and sintered in a vacuum (650 °C, 1 h). With PCAP content in the cermet composition from 3 to 15 % by weight, a material with a density of 2.58…2.67 g/cm3 and a bending strength of 380…450 MPa was obtained. Cermet has anisotropy of hardness values. The maximum values of hardness HV and HRB were achieved with a PCAP content of 9 % by weight (HVmax – 1970 and 1460 MPa at an indenter load of 0.25 and 1.00 N respectively; HRBmax – 44). The material can be used as lightweight armor protection elements, wear-resistant elements and special abrasive tools.
The article presents the results of a comprehensive study of the physicochemical properties of wollastonite raw material from the Koitash mine, located in the Gallaaral district of the Jizzakh region of Uzbekistan. The chemical-mineralogical composition, physicochemical characteristics, and crystal structure of wollastonite have been determined using modern methods of physicochemical analysis. It is shown that the wollastonite of the Koitash mine is a promising natural resource that can be widely used in the ceramic and construction industries of the Republic.
Ba2NaNb5O15 (BNN) ceramics were synthesized by the solid-state reaction method and investigated for their structural and dielectric properties. X-ray diffraction confirmed the formation of a single-phase orthorhombic structure (Cm2m space group). A sharp dielectric anomaly near 450 °C was observed, corresponding to the ferroelectric–paraelectric transition. Curie–Weiss and modified Curie–Weiss analyses indicated a first-order transition with moderately diffuse character (? ? 1.5). AC conductivity exhibited frequency dispersion consistent with Jonscher’s universal power law. The temperature dependence of the fitting parameters and extracted activation energies revealed that charge transport is dominated by thermally activated hopping, in agreement with the Correlated Barrier Hopping (CBH) model. These findings provide new insights into the dielectric response and charge transport mechanisms of BNN ceramics, highlighting their potential for ferroelectric and optoelectronic applications.
