In this work, the structural, electrical, and mechanical properties and phase composition of high-content cubic zirconium oxide ceramics stabilized with Ca were investigated. The novelty of this work lies in evaluating the potential use of porous ceramics obtained using calcium carbonate as a matrix for dispersed nuclear fuel. Experimental samples were prepared using solid-phase synthesis through sintering in air at 1500 °C. The X-ray diffraction method and Raman spectroscopy showed that the fraction of the cubic zirconium oxide ZrO₂-c phase gradually increased as the mass concentration changed from C_w = 0.00 to C_w = 0.15, and the CaZrO₃ phase was present at concentrations of C_w = 0.20 and C_w = 0.25. When the phase composition was altered, significant changes occurred in the internal microstructure of the ceramics due to the processes of grain sintering and pore formation. Quantitative XRD analysis demonstrated the incorporation of Ca into the cubic structure of the ZrO₂-c polymorph. Dielectric spectroscopy at low frequencies revealed that the synthesized ceramics had a dielectric constant of 16.8–22 with a low dielectric loss of ~ 0.005. The microhardness value at a load of 200 kgf (HV0.2) of the obtained samples varied between 5 and 12 GPa and depended on the internal microstructure and phase composition. The obtained results clearly indicate that the mechanical and electrical properties and phase composition of synthesized ceramics make them suitable as a matrix for dispersed nuclear fuels.

In this work, ceramic samples of cerium oxide doped with yttrium were investigated. The concentration of a dopant Y(NO₃)₃ varied from 5 to 25 wt% in the initial charge. In the course of the experiment, a simple method was developed to obtain ceramics with a porosity of ~20% via one-step annealing in air in a muffle furnace. For comparison, samples with two annealings were also synthesized to determine the effects of pores on electrical, structural, and mechanical characteristics. The obtained samples were examined via X-ray powder diffraction, scanning electron microscopy, X-ray energy dispersive spectroscopy, Raman spectroscopy, dielectric spectroscopy, and Vickers microhardness measurements. The substitution of Ce⁴⁺ ions with Y³⁺ ions led to a significant decrease in the lattice parameter, average crystallite size, and average grain size, with a simultaneous increase in the lattice defectivity, dielectric constant, electrical conductivity, and microhardness values. It is shown that samples with a dopant weight fraction of 0.05–0.15 and one-step annealing have favorable electrical and mechanical characteristics for energy applications as porous materials with ionic conductivity.

Climate change remains one of the most critical global challenges, largely driven by the rise in atmospheric CO2 levels. Effective strategies for capturing and utilizing CO2 are crucial to mitigate its environmental impact. Metal–organic frameworks (MOFs), particularly HKUST-1 (MOF-199), are promising materials due to their high surface area, porosity, and tunable properties. In this study, HKUST-1 was successfully immobilized on polyethylene terephthalate (PET) track-etched membranes, leveraging the membranes’ well-defined porosity and chemical stability. Membrane characterization via SEM revealed uniform coverage of octahedral HKUST-1 crystals with sizes ranging from 0.15 μm (inside the pores) to 1.5–5 μm (on the surface of the membrane). BET analysis of the PET TeMs-HKUST-1 composite membrane indicated a specific surface area of up to 382 m2/g. XRD confirmed the crystallinity of the HKUST-1 structure. The composite membranes exhibited CO2 sorption capabilities, with an adsorption capacity of 0.53 ± 0.03 mmol/g (after 1 h of adsorption) in the first cycle for the solvothermal method and 0.31 ± 0.02 mmol/g (after 1 h of adsorption) for the solvoshaker method. Durability tests demonstrated a stable performance over 12 adsorption–desorption cycles. These results highlight the potential of PET TeMs-HKUST-1 composite membranes for scalable and efficient CO2 capture, contributing to the development of sustainable solutions for addressing climate change.

The aim of this work is to study the structural, dielectric, and mechanical properties of aluminum oxide ceramics with the triple sintering additive 4CuO-TiO₂-2Nb₂O₅. With an increase in sintering temperature from 1050 to 1500 °C, the average grain size and the microhardness value at a load of 100 N (HV0.1) increased with increasing density. It has been shown that at a sintering temperature of 1300 °C, the addition of a 4CuO-TiO₂-2Nb₂O₅ additive increases the low-frequency permittivity (2–500 Hz) in alumina ceramic by more than an order of magnitude due to the presence of a quadruple perovskite phase. At the same time, the density of such ceramics reached 89% of the theoretical density of α-Al₂O₃, and the microhardness value HV0.1 was 1344. It was observed that the introduction of 5 wt.% 4CuO-TiO₂-2Nb₂O₅ in the raw mixture remarkably increases values of shrinkage and density of sintered ceramics. Overall, the results of this work confirmed that introducing the 4CuO-TiO₂-2Nb₂O₅ sintering additive in the standard solid-phase ceramics route can significantly reduce the processing temperature of alumina ceramics, even when micron-sized powders are used as a starting material. The obtained samples demonstrated the potential of α-Al₂O₃ with the triple additive in such applications as electronics, microwave technology, and nuclear power engineering.

Ceramics based on zirconium dioxide are very important compounds for dental, implant, and structural material applications. Despite the fact that tetragonally stabilized YSZ has been well studied, the search for new compositions of zirconia-based ceramics is still in progress. The ZrO₂-CeO₂ system is one of the alternatives for YSZ materials, but there is conflicting experimental data on its phase composition and mechanical properties depending on the ratio of components. In this study, we investigated the phase composition, and microstructural, mechanical, and physical properties of (1 − x)∙ZrO₂-x∙CeO₂ (step of x = 0.05) ceramics obtained by the solid-state sintering process from micron-sized powders. For the characterization of samples, XRD, Raman spectroscopy, SEM, the Vickers Microhardness Test, and dielectric spectroscopy were implemented. The results showed that by varying the CeO₂ concentration, it is possible to synthesize stable tetragonal ZrO₂ at room temperature with a high microhardness HV0.05 value of ~1500, low porosity (~2.5%), and a high dielectric constant of 36. The pronounced combined effect of tetragonal phase formation, densification, and grain size reduction on the mechanical and dielectric properties of the experimental samples was investigated. Refined experimental data make it possible to synthesize high-quality zirconia–ceria ceramics for use as refractories, dispersed nuclear fuel, or solid oxide fuel cells.