Ректорат УДУНТ
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ENG: Rectorate of the USUST
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Item Effects of Composition on the Structure, Thermal and Some Physical Characteristics of Bi2O3-B2O3-ZnO-SiO2 Glasses(S.C. Virtual Company of Physics S.R.L, Romania, 2024) Hordieiev, Yu. S.; Zaichuk, A. V.ENG: The influence of composition on the structure, thermal, and some physical characteristics of bismuth borate glasses, formulated as 55Bi2O3–(35-x-y)B2O3–(5+x)ZnO–(5+y)SiO2 (where 0 ≤ x, y ≤ 15 mol%), was investigated. Comprehensive analyses were conducted using techniques such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), Differential Thermal Analysis (DTA), and Dilatometry. XRD confirmed the amorphous nature of the glass samples, while FTIR spectroscopy revealed that the glasses are primarily composed of BO4, BO3, BiO6, BiO3, ZnO4, and SiO4 structural units. DTA provided further evidence of the samples' glassy state and insights into key temperatures like glass transition (T g), crystallization (T c), and melting (T m). The study finds that substituting B2O3 with SiO2 increases all characteristic temperatures, whereas replacing it with ZnO decreases T g and T c but increases T m. The maximum thermal stability, indicated by a ΔT of 99°C, was observed in the glass with a 55Bi2O3–20B2O3–20ZnO–5SiO2 composition. Dilatometric measurements showed that the investigated glasses have a high coefficient of thermal expansion (10.0–10.7 ppm/°C) values, a low glass transition temperature (345–376°C), and a low dilatometric softening temperature (364–392°C). Additionally, the density and molar volume of the samples were accurately determined.Item Impact of Aluminum Fluoride Addition on Crystallization, Structure and Thermal Properties of Lead Borate Glasses(S.C. Virtual Company of Physics S.R.L, Romania, 2024) Hordieiev, Yu. S.; Zaichuk, A. V.ENG: The glass composition (70-x)PbO–(30-y)B2O3–(x+y)AlF3, where x and y ranges from 0 to 20 mol%, were prepared using the conventional melt-quenching-annealing technique. The structural and thermal properties of the glasses were comprehensively analyzed using techniques like Differential Thermal Analysis (DTA), Dilatometry, Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). XRD confirmed the amorphous, non-crystalline structure of the glasses. The glass network was found to be composed of structural units such as PbO4, BO4, BO3 and AlO6 using FTIR spectroscopy. FTIR analysis revealed significant structural changes, including the transformation of BO4 to BO3 units and the increase in non-bridging bonds, particularly with higher AlF3 content. DTA was instrumental in determining characteristic temperatures, such as the glass transition, melting, and peak crystallization temperatures, along with glass stability parameters (∆T, Hr, Tgr) for all samples. The study found that the addition of AlF3 led to a decrease in these characteristic temperatures when replacing B2O3, but an increase when replacing PbO. Variations in the density and thermal expansion of the lead borate glass were observed upon the addition of AlF3, decreasing when substituting for PbO and increasing when substituting for B2O3. These findings provide insights into the properties of oxyfluoride glasses, paving the way for future optimization in their composition for varied applications.Item Lanthanum-Doped Zinc Borate Glasses: Fabrication, Structural Analysis, Thermal Properties, and Gamma Radiation Shielding Performance(S.C. Virtual Company of Physics S.R.L, Romania, 2025) Hordieiev, Yu. S.; Zaichuk, A. V.ENG: Zinc borate glasses with a composition formula of (60-m)B₂O₃–40ZnO–mLa₂O₃ (m = 0, 3, 6, 9, 12, and 15 mol%) were synthesized via the melt-quenching technique for the purpose of investigating the effects of La₂O₃ incorporation on their structural, thermal, and radiation shielding properties. Amorphous structures for all samples (coded as ZBLa0 to ZBLa15) were confirmed using X-ray diffraction and Differential thermal analysis. Incorporating La₂O₃ significantly influenced the glass matrix, increasing density, molar volume, thermal expansion and the glass transition, while decreasing the crystallization peak temperature and thermal stability. These effects highlight La₂O₃'s role as a network modifier that depolymerizes the glass structure, as indicated by shifts in FT-IR bands and altered vibrational modes. Radiation shielding properties improve markedly with La₂O₃ addition, as evidenced by increased mass attenuation coefficients and effective atomic numbers, making the glass with 15 mol% La₂O₃ (ZBLa15) particularly effective at gamma-ray attenuation across a wide photon energy range. These findings suggest that La₂O₃-doped zinc borate glasses are highly suitable for applications requiring enhanced radiation shielding alongside reliable thermal performance.Item Preparation and Characterization of Strontium-Doped Bismuth Borate Glasses(S.C. Virtual Company of Physics S.R.L, Romania, 2024) Hordieiev, Yu. S.; Zaichuk, A. V.ENG: Employing the melt quenching method, new bismuth borate glass compositions denoted as (40+x)Bi2O3–(60-x-y)B2O3–ySrO, with x and y ranging between 0 to 20 mol%, were synthesized. The X-ray Diffraction analyses confirmed the amorphous nature of all glass samples, indicating the absence of long-range order typically seen in crystalline materials. Concurrently, the Fourier-transform Infrared Spectroscopy examinations unveiled the existence of fundamental structural units within the glasses, including BO3 and BO4 trigonal and tetrahedral units, as well as BiO3 and BiO6 polyhedra, suggesting a complex network structure. Differential Thermal Analysis (DTA) and dilatometry assessed the glasses' thermal properties. DTA demonstrated the glasses' high thermal stability, with a stability value of up to 106°C, noting that stability improves with more SrO. Dilatometry analyses revealed these glasses exhibit a high thermal expansion coefficient, ranging from 8.69 to 10.7 ppm/°C, alongside relatively low glass transition temperatures between 362 and 432°C and dilatometric softening temperatures spanning from 380 to 447°C. Density measurements were conducted, followed by molar volume and oxygen packing density calculations, to glean further insights into the samples. Compared to other heavy-metal oxide glasses, the glasses examined in this study exhibited notably high-density values, ranging between 6.279 and 7.476 g/cm3.