Browsing by Author "Bila, Оlena V."

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    Influence of Synthesis pH on Structural, Dielectric and Magnetic Properties of MnFe2O4
    (Oles Honchar Dnipro National University, Dnipro, 2025) Frolova, Liliya A.; Saltykov, Dmytro Yu.; Holub, Iryna V.; Bila, Оlena V.
    ENG: Dispersed manganese ferrite particles were obtained by a combined co-precipitation method at different pH of the initial solution (7–12). The structural, morphological, optical and magnetic properties of the synthesized nanoparticles were characterized using X-ray diffraction, scanning electron microscopy, and vibrational magnetometry. The XRD results showed that MnFe2O4 has a cubic spinel crystal structure with an average crystallite size of 14–65 nm. The presence of additional phases is observed at low pH and pH greater than 12. Ferritization significantly depends on pH, which affects the phase composition of the products and the size of the crystallites. In addition, with an increase in pH from 7 to 12, the percentage of microstresses and the density of dislocations decreases. The obtained MnFe2O4 samples exhibit ferrimagnetic properties, the highest saturation magnetization value of 56.8 Emu/g is achieved at pH 10. In addition, the coercive force changes from 5 to 50 Oe with increasing pH due to the increase in crystallite size.
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    Study of the Effect of Gaseous Elements on Metal Macrostructure during Cooling
    (Ukrainian State University of Science and Technologies, Dnipro, 2025) Holub, Iryna V.; Bila, Оlena V.
    ENG: The article presents a study of the influence of gas elements (oxygen, hydrogen and nitrogen) during metal processing with a mixture of gases (argon, nitrogen) on the macrostructure of the metal after cooling. One of the most common methods of ladle processing of steel is the process of blowing metal with inert gases and its vacuuming. A mathematical model has been developed that allows us to consider the process of gas removal and calculate the quantitative indicators of the removal of dissolved gases from the metal during its processing. Taking into account the thermodynamic and kinetic features of the dissolution of gases in the metal during blowing metal in the ladle with inert gases and during vacuuming allowed us to clarify the physicochemical processes of gas behavior in the metal, which will lead to the possibility of developing a new technology of ladle processing of metal using mixtures of inert gases.