The Physical Model of Formation of Hexagonal Ferrites BaFe12O19

To identify the features of structural transformations occurring during the formation of the crystal lattice of hexagonal barium ferrite were studied the following issues: a) component defined that are structural element in the reaction of solid-phase synthesis of ferrites BaFe12O19; b) the phase composition set of the reaction products formed in mixtures of BaCО3 – Fe2O3; c) a crystal-chemical model developed allows visually describe the transformation of -Fe2O3 – BaFe12O19

The Physical Model of Formation of Hexagonal Ferrites BaFe12O19

To identify the features of structural transformations occurring during the formation of the crystal lattice of hexagonal barium ferrite were studied the following issues: a) component defined that are structural element in the reaction of solid-phase synthesis of ferrites BaFe12O19; b) the phase composition set of the reaction products formed in mixtures of BaCО3 – Fe2O3; c) a crystal-chemical model developed allows visually describe the transformation of -Fe2O3 – BaFe12O19

Influence of Magnetic Pulseprocessing on Oxide Materials Physics and Mechanical Properties

Internal stresses, specific single-crystal blocks, stoichiometric impurity of oxides composition and other factors lead to low strength properties of ferromagnetic iron oxides. Weakening of such defects and increa s-ing iron oxides microhardness, their fracture and mechanic strength are possible by using magnetic pulse processing. The results of experimental studies of the magnetic pulse field effecting on the iron oxides strength properties are shown. Mössbauer spectroscopy, porosimetry, X-ray structure analysis are used to find the mechanisms of this effect. The strength properties change is the result of set of microscopic and quantum effects superposition. It provides easy defects restructuring of solids: vacancies, dislocations, voids. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3636

Magnetic Properties and Local Parameters of Crystal Structure for BaFe[12]O[19] and SrFe[12]O[19] Hexagonal Ferrites

It is shown that difference between magnetic properties of hexagonal ferrites BaFe[12]O[19] and SrFe[12]O[19] is connected with difference of electronic configurations of Ba2+ and Sr2+ ions, and their ionic radii. Replacement of Ba2+ ions by Sr2+ ions that are smaller in size effects the degree of distortions of octahedrons located either in a hexagonal R-block or at its boundary with S-block. It contributes to a preferred localization of electrically active vacancies at the boundary of R- and S-block

The Formation and Study of the FeCo Nanoparticles Alloy in Structure of Metal-Carbon Nanocomposites FeCo/C

The study of the peculiarities of the formation of the nanoparticles FeCo-alloy in the composition of metal-carbon nanocomposites FeCo/C. Structure, phase composition and kinetic processes of synthesis of nanocomposites FeCo/C by methods of Mossbauer spectroscopy were studied. This allowed us to establish the peculiarities of formation of nanoparticles FeCo alloy in the composition of the nanocomposites. The nanocomposites were synthesized by the IR-pyrolysis at temperatures of precursors of 300 - 800 °C on the basis of polyacrylonitrile (PAN), iron acetylacetonate and cobalt acetate. Also it is established that an increase in the average size of nanoparticles FeCo with increasing temperature synthesis is occurred. In the temperature range of synthesis of 600-800 °C the size varies from 9- 10 to 16-18 nm, respectively. The features the phase transitions and phase composition of the metal-carbon nanocomposites FeCo / C were studied by Mossbauer spectroscopy. Nanocomposites were synthesized in the temperature range of T = 300-800 °C. It was shown that the samples synthesized at T = 300 °C contains of superparamagnetic nanoparticles of magnetite and amorphous oxide of iron only. The process of forming nanoparticles of alloy FeCo occurs within the temperature range 500-600 ° C due to the recovery of amorphous iron oxide and magnetite as well as them dissolving in a phase of cobalt. The growth of size of nanoparticles of alloy by agglomeration and dissolution of iron in the alloy nanoparticles occurs only at the temperature range of synthesis 600-800 ° C. This is confirmed by a decrease of the content of Fe, which associated with carbon and it is consistent with the results of phase and structural studies, carried out in previous works

THE STUDY OF PHASE COMPOSITION OF HIGHLY COERCISE ALLOYS WITH Fe-Ni-Al-CO-Ti AS THE BASE BY MEANS OF γ-RESONANCE SPECTROSCOPY

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Magnetic Microstructure Aluminum-substituted Barium Hexaferrite for Microwave Devices mm-Wavelength Range

The magnetic structure and cationic distribution was investigate in ferrite with a hexagonal structure BaFe12 – хAlхO12 (х ≤ 2). It is found that when х = 2 Al3+ ions are localized mainly in the positions of 12k (а-sublattice) and 4f1 (с-sublattice). This contribute to change of number magnetically active connections and therefore the magnetic structure of ferrite and magnetic parameters. It was concluded about the possibility of using the results obtained with the choice of optimal composition of substrates for millimeter-wave devices