This study explores the role of MgO, ZnO, and BaO additions in tuning the structural features and radiation shielding efficiency of Dy3+-doped B2O3-Bi2O3-K2O glasses fabricated by melt quenching, with emphasis on photon energies corresponding to Cs-137, Co-60, and Na-22 sources. The parent composition (64.5 B2O3-15 Bi2O3-20 K2O-0.5 Dy2O3, mol %) was modified by substituting 10 mol % of B2O3 with MgO, ZnO, or BaO. The density increased from 4.07 g cm-3 in the Mg-containing glass to 4.21 g cm-3 in the Ba-containing sample, indicating a clear enhancement. By using XRD, infrared spectroscopy, UV-Vis tests, and computational modeling, the relationship between structural changes and functional performance was systematically examined. The results indicate that by enhancing [BO4] formation with its potent charge compensation, the inclusion of Mg2+ enhanced the network's integrity, resulting in improved mechanical strength (elastic modulus = 103 GPa; shear modulus = 41 GPa). In contrast, although Ba2+ reduces mechanical strength, it provides superior radiation shielding performance, requiring only a 0.433 cm half-value layer at 0.284 MeV. While the radiation shielding properties vary across the prepared glasses, each composition demonstrates improved performance relative to conventional tellurite- and lanthanum oxide-based glasses, underscoring the role of precise compositional design in achieving multifunctionality. The results confirm that all prepared glasses have potential as radiation shielding materials, with the Mg2+-containing composition being particularly well-suited for uses demanding superior mechanical strength and structural robustness.
Work has been continued to expand the powder pre-infiltration technology for the manufacture of layered carbon-ceramic composites with matrices based on ultra-high temperature ceramics. The innovative feature of the proposed approach lies in the fact that, following the fabrication of filled carbon fiber preforms, all subsequent processing stages are fully carried out within the standard processing route for Cf/C composites (f-fibers). Composites of Cf/C-HfB2-20 vol % SiC and Cf/C-ZrB2-20 vol % SiC compositions with open porosity, ultimate strength, and flexural elastic modulus of 10-12%, 98-104 MPa, and 6.5-7.0 GPa, respectively, were prepared. The results of their fire tests at surface temperature T w = 2300 degrees C under the influence of a high-speed air-gas flame flow lasting 500 s are presented. The average rate of linear material removal of composites as a result of ablation was 1.2 and 2.8 & micro;m/s, respectively. The mechanisms of ablation resistance of composites have been established. It is shown that the in situ formation of a multilayer heterogeneous structure of oxide films causes a change in the oxidation from kinetic to diffusion mode. It is found that the substitution of ZrB2 for HfB2 in the composite matrix accelerates the counter mass transfer of reagents through the film and reduces resistance to ablation. The main reasons for this are analyzed.
Fundamental concepts about the structure of matter have been analyzed based on cause-and-effect relations leading to the postulates of quantum mechanics. The interpretation of the characteristics of a vacuum as properties of a universal carrier medium in terms of fluid mechanics has made it possible to select consistent models of the basic objects of condensed matter. The development of concepts of the structure of the photon and electron has been supplemented by descriptions of the processes of their production and transformation. The nature of electric charges and the picture of their interaction through volumetric interference fields have been discussed. The details of the structure of the atom, the sizes of electron orbits, and the internal characteristics of some elementary particles have been clarified. The physical nature of the quantization of matter at different dimensional and energy levels has been determined. The proposed solutions to problems of a quantum can be useful for the range of physicists dealing with problems that are fundamentally unsolvable in traditional terms.
Tin-based perovskite solar cells (PSCs) have emerged as a compelling, low-toxicity alternative to traditional lead- based counterparts. Among these, the organic-inorganic metal halide formamidinium tin triiodide FASnI3 is particularly noteworthy due to its high theoretical efficiency, superior stability, cost-effective production, and facilitated solution-based fabrication. In this study, we employed the SCAPS-1D simulation framework to rigorously model FASnI3 PSC performance across four critical architectural parameters. The optimized device demonstrated exceptional performance and robust stability, yielding an open-circuit voltage V oc of 1.16 V and a short-circuit current density J sc of 31.70 mA/cm2. Furthermore, detailed investigation into the charge carrier capture cross-section resulted in a peak power conversion efficiency (PCE) of 32.47% and a fill factor (FF) of 88.53%. These findings provide a strategic pathway for the development of high-performance, lead-free perovskite photovoltaics.
This paper proposes a new method for estimating the elastic modulus of protective polymer coatings based on standard tensile tests on three-layer strip specimens. The proposed method derives the coating’s elastic modulus from a comparison of experimental elastic modulus values obtained for the base material (08 PS steel) and the effective elastic modulus for specimens coated with the studied coatings. The differences between these values are 10–15
