Influence of the BaFe12O19 Crystal Surface on the Interparticle Magnetic Interaction

The influence of the physicochemical state of the particle surface on the interparticle magnetic interaction in a closepacked system of singledomain microcrystals of highly anisotropic hexaferrite BaFe12O19 has been studied. The efficiency of the used technique of treatment of the particle surface with acid and alkali solutions has been determined from the data on the Fe3+ ion concentration in the solution and on the change in the elemental composition in the nearsurface layer. It has been shown that, when the etched layer thickness is 2.5c (c is the lattice parameter of ferrite), the parameter of the resulting interparticle interaction changes qualitatively and quantitatively. The technologically accessible technique used allows the attenuation of the interparticle magnetic interaction in a system of closepacked particles by several times. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3518

Influence of the BaFe12O19 Crystal Surface on the Interparticle Magnetic Interaction

The influence of the physicochemical state of the particle surface on the interparticle magnetic interaction in a closepacked system of singledomain microcrystals of highly anisotropic hexaferrite BaFe12O19 has been studied. The efficiency of the used technique of treatment of the particle surface with acid and alkali solutions has been determined from the data on the Fe3+ ion concentration in the solution and on the change in the elemental composition in the nearsurface layer. It has been shown that, when the etched layer thickness is 2.5c (c is the lattice parameter of ferrite), the parameter of the resulting interparticle interaction changes qualitatively and quantitatively. The technologically accessible technique used allows the attenuation of the interparticle magnetic interaction in a system of closepacked particles by several times. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3518

Structural Transformations of Ni<inf>1 –</inf><inf>x</inf>Cu<inf> x</inf>Fe<inf>2</inf>O<inf>4</inf> Nanoparticles Depending on the Number of Cu Ions

© 2020, Pleiades Publishing, Ltd. Abstract: Changes in the structure and properties of the Ni1 – xCuxFe2O4 ferrites-spinel magnetic nanoparticles depending on the Cu ion concentration (0 ≤ x ≤ 1.0) have been studied using Mossbauer spectroscopy. It has been found that, with the increasing of the Cu ion concentration, the structure of nanoparticles changes from the structure of reverse spinel (NiFe2O4) to that of mixed spinel (CuFe2O4). It has been shown that the hydrothermal synthesis method makes it possible to obtain single-phase nanoscale particles with a very narrow size distribution and ideal magnetic ordering, which are promising for biomedical applications. The relationship between the distribution of cations on sublattices, the value of the inversion parameter, and the Cu ion concentration has been established

The Composition and Magnetic Structure of Fe<inf>3</inf>O<inf>4</inf>/γ-Fe<inf>2</inf>O<inf>3</inf> Core-Shell Nanocomposites under External Magnetic Field: Mössbauer Study (Part II)

© 2020, Pleiades Publishing, Ltd. Abstract: The composition and the magnetic structure of Fe3O4/γ-Fe2O3 nanoparticles placed into external magnetic field with a strength of 1.8 kOe are studied with Mössbauer spectroscopy. We showed that the thickness of the maghemite (γ-Fe2O3) shell can be changed by the synthesis conditions. We found that there is a layer, in which the magnetic moments are not oriented collinearly to those located in the depth of the shell, on the surface of maghemite (γ-Fe2O3) shell in the Fe3O4/γ-Fe2O3 nanocomposites; in other words, there is a canted spin structure. An intermediate layer in the spin-glass state is formed between the core and the shell. The data on structure of core/shell particles are important to understand the properties of nanocomposites, which are of great interest to apply in various fields, including biomedicine

The Composition and Magnetic Structure of Fe<inf>3</inf>O<inf>4</inf>/γ-Fe<inf>2</inf>O<inf>3</inf> Core–Shell Nanocomposites at 300 and 80 K: Mössbauer Study (Part I)

© 2020, Pleiades Publishing, Ltd. Abstract: The magnetic structure and the composition of Fe3O4/γ-Fe2O3 nanoparticles are studied at 300 and 80 K with Mössbauer spectroscopy. We found that the Fe3O4/γ-Fe2O3 particles are a core–shell nanocomposite (NC), in which magnetite Fe3O4 is covered with a maghemite shell (γ-Fe2O3). We showed that the thickness of the maghemite shell (γ-Fe2O3) depends on synthesis technology. We found that a layer, whose magnetic structure differs from that of the inner part of the shell (γ-Fe2O3), is formed on the surface of the maghemite shell (γ-Fe2O3) in the Fe3O4/γ-Fe2O3 NC. An intermediate layer is formed in the spin-glass state between the core and the shell. The data on structure of core–shell nanocomposites open up prospects to explain the properties of such particles, which are of great interest to use in various fields, including biomedicine

Magnetic Nanocomposites Graphene Oxide/Magnetite + Cobalt Ferrite (GrO/Fe<inf>3</inf>O<inf>4</inf> + CoFe<inf>2</inf>O<inf>4</inf>) for Magnetic Hyperthermia

Abstract: In this study we have investigated new magnetic nanocomposites (MNCs) graphene oxide (GrO)/magnetite (Fe3O4) + cobalt ferrite (CoFe2O4) of various concentrations that were synthesized by the mechanochemical method—the process of mechanical grinding in a ball mill in the aqueous medium of graphene oxide and preliminarily synthesized powders of magnetite and cobalt ferrite. We have obtained and studied MNCs GrO/Fe3O4 + CoFe2O4 obtained by grinding with various contents of components (in wt %), namely: 50/40 + 10; 50/25 + 25; 50/10 + 40; and 50/0 + 50. The synthesized MNCs GrO/Fe3O4 + CoFe2O4 have been investigated by X-ray diffraction method, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, a vibrating sample magnetometer, and Mössbauer spectroscopy. With the help of Mössbauer investigations, the phase composition, magnetic state, and structure of synthesized MNCs GrO/Fe3O4 + CoFe2O4 have been established, which is important for creating high-performance materials for various applications. The heterogeneity of the MNCs obtained opens prospects for their biomedical applications

Graphene Oxide/Iron Oxide (GrO/FeOx) Nanocomposites for Biomedicine: Synthesis and Study

Abstract: The properties and structure of magnetic graphene oxide GrO/iron oxide FeOx nanocomposites synthesized by the mechanochemical method with different content of components GrO : FeOx (wt %), namely, 20 : 80, 50 : 50, and 80 : 20 were studied. The method of mechanochemical synthesis is a mechanical process of grinding iron oxide powder together with graphene oxide in a ball mill in an aqueous medium. The synthesized magnetic GrO/FeOx nanocomposites were studied by Raman spectroscopy, a vibrating sample magnetometer, and Mössbauer spectroscopy. The Mössbauer studies made it possible to determine the phase composition and structure of the synthesized magnetic GrO/FeOx nanocomposites. The data of Mössbauer spectroscopy showed that the GrO/FeOx composites consist of the magnetite phase Fe3O4 and magnetic nanoparticles in the paramagnetic state, which is consistent with the data of X-ray diffraction studies. Based on the results of Mössbauer spectroscopy, it was found that, in addition to magnetite, the magnetic GrO/FeOx nanocomposites contain hematite α-Fe2O3, as well as phases identified as iron carbides and iron-depleted carbon clusters. The latter were not detected by X-ray diffraction, apparently because their number is insignificant and they are in an amorphous state. The results obtained show that graphene is not just a source of carbon during grinding in a ball mill, but has its own reactivity and the ability to generate new phases during mechanochemical activation. Based on the performed Mössbauer spectral studies, we obtained unique and important information on the magnetic structure of the magnetic GrO/FeOx nanocomposites. The research results make it possible to explain the magnetic properties of magnetic nanocomposites, GrO/magnetic particles, which is important for the development and graphene oxide-based synthesis of high-performance magnetic nanocomposites for various applications, including biomedicine