Impact of Gadolinium on the Structure and Magnetic Properties of Nanocrystalline Powders of Iron Oxides Produced by the Extraction-Pyrolytic Method (original) (raw)
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It has been observed that, compared to bulk form, the nanocrystalline ␣-Fe 2 O 3 is finding application in various areas. Magnetic properties of ␣-Fe 2 O 3 are found to be influenced by the size of particles and are also sensitive to synthesis method employed for sample preparation. In the present work we have prepared a series of Nd doped ␣-Fe 2−x O 3 samples (x = 0.0-0.5) by combustion method, without using any fuel. The analysis of room temperature neutron diffraction patterns shows that all the compounds of the series form in the hematite (␣-Fe 2 O 3 ) structure, space group R−3c. Magnetization measurements show that there is a broad distribution of particle size in the samples. We find that the increase in the Nd content results in the dilution of magnetism of ␣-Fe 2 O 3 . From results we believe that inclusion of Nd in ␣-Fe 2 O 3 drastically modifies the magnetic properties.
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We have prepared α-iron and magnetite (Fe 3 O 4) nanoparticles in MgO matrix from a mixture of nanocrystalline Fe 2 O 3 with Mg(H,O) powders calcinated in hydrogen. This procedure yielded spherical magnetic nanoparticles embedded in MgO. Transmission electron microscopy and Mössbauer spectroscopy were used for structure and phase analysis. The measurements of magnetic properties showed increased coercivity of the nanocomposite samples. Keywords nanocrystalline materials • magnetite • α-Fe • nanocomposite • magnetic properties.
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Magnetic iron oxide particles are used for in vitro diagnostics for nearly 40 years. Due to their unique physical, chemical, thermal and mechanical properties, as well as biocompatibility and low toxicity in the human body, iron oxide nanoparticles have been used in many biomedical applications, such as contrast agents for magnetic resonance imaging, carriers for controlled drug delivery and immunoassays, but also in magnetic hyperthermia. Our aim is to investigate the effect of pressure and temperature on the structural, thermal and magnetic properties of iron oxide nanomaterials prepared by hydrothermal synthesis. Iron oxide nanoparticles were synthesized at temperatures of 100-200°C and pressures of 20-1000 bar. It has been found that pressure influences the type of iron oxide crystalline phase. Thus, for lower pressure values (< 100 bar), iron oxide is predominantly formed as hematite, while at pressures > 100 bar, the major crystalline phase is goethite. The complex therm...
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Journal of Alloys and Compounds, 2021
In this study, iron oxide nanoparticles (NPs) were successfully prepared from three different reactive systems by using mechanochemical synthesis. The effect of using iron salts with different oxidation state and the addition of metallic Fe to the mixture reactive was investigated. The influence of different mechanochemical treatments times on the structural and magnetic properties of the obtained iron oxide NPs was also studied. Composition, crystal structure and morphology of the nanoparticles were analyzed by XRD, Raman spectroscopy, SEM, TEM and DLS techniques. The obtained crystalline NPs exhibited mean sizes of about 8e10 nm and agglomerate in clusters of about 300 nm. Also, magnetic properties as a function of temperature and applied field were determined for the obtained iron oxide NPs, showing high magnetization in the whole temperature range. The results indicated that the presence of metallic Fe in the starting mixture plays a crucial role in the formation of spinel magnetic phases (magnetite/ maghemite). Structural and magnetic results are consistent with the formation of maghemite in the studied samples.
A review of Structure, Properties, and Chemical Synthesis of Magnetite Nanoparticles
Journal of applied sciences and nanotechnology, 2023
In recent years, extensive studies have been devoted to iron oxide nanoparticles (IONPs). Iron oxides are chemical compounds that have various polymorphic forms, including maghemite (γ-Fe2O3), magnetite (Fe3O4), and Hematite (α-Fe2O3). Among them, the most important studied is magnetite (Fe3O4) due to its low cost and low toxicity and its unique magnetic and physicochemical characteristics, which qualify it for use in various biomedical and technological applications. Magnetic particles should be small and have a narrow size distribution for these applications. The smaller the size of the iron oxide particles, the greater their reactivity and biodegradability. In this review, we display summary information on magnetite (Fe3O4) nanoparticles in terms of structure, characteristics, and preparation methods. Because the prepared strategy has been proven to be critical for preferable control of the particle size and shape, in addition to producing monodispersed magnetite (Fe3O4) nanoparticles with a direct effect on their characteristics and applications, special attention will be placed on chemical preparation techniques including Hydrothermal synthesis, Coprecipitation technique, Sol-Gel process, and thermal decomposition method. This review offers specific information for selecting appropriate synthetic methods for obtaining appropriate sizes, shapes, and magnetic properties of magnetite (Fe3O4) nanoparticles (NPs) for target applications.
Structure and magnetic properties of biogenic ferrihydrite nanoparticles doped with gadolinium
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