Energetic Electron-Assisted Synthesis of Tailored Magnetite (Fe3O4) and Maghemite (γ−Fe2O3) Nanoparticles: Structure and Magnetic Properties

Abstract

Iron oxide nanoparticles with a mean size of approximately 5 nm were synthesized by irradiating micro-emulsions containing iron salts with energetic electrons. The properties of the nanoparticles were investigated using scanning electron microscopy, high-resolution transmission electron microscopy, selective area diffraction and vibrating sample magnetometry. It was found that formation of superparamagnetic nanoparticles begins at a dose of 50 kGy, though these particles show low crystallinity, and a higher portion is amorphous. With increasing doses, an increasing crystallinity and yield could be observed, which is reflected in an increasing saturation magnetization. The blocking temperature and effective anisotropy constant were determined via zero-field cooling and field cooling measurements. The particles tend to form clusters with a size of 34 nm to 73 nm. Magnetite/maghemite nanoparticles could be identified via selective area electron diffraction patterns. Additionally, goethite nanowires could be observed.

Radiation-Induced Synthesis and Superparamagnetic Properties of Ferrite Fe3O4 Nanoparticles

“…The size is smaller than those observed for Fe 3 O 4 nanoparticles also formed under irradiation at 30 kGy in the presence of PA (D~30 nm) [ 51 ] or synthesized through other methods [ 52 ]. Nevertheless, it is close to that observed for nanoparticles synthesized by radiolytic means in the presence of AG ( Figure S4 ), dextran [ 53 ], or Triton-X [ 26 ]. It should be noted that, with the same stabilizer PA, the sizes of nanoparticles are much smaller (5.2 nm) ( Figure 9 ) when synthesized using the radiolytic route than by coprecipitation (11 nm) ( Figure S3 ), despite a much lower concentration of PA was used (3 × 10 −3 instead of 0.5 mol L −1 ).…”

“…Recent studies have demonstrated that superparamagnetic iron ferrite Fe 3 O 4 nanoparticles [ 26 , 27 ] and cobalt ferrite CoFe 2 O 4 nanoparticles [ 28 ] can be synthesized using radiolysis.…”

Recyclable Fe3O4 Nanoparticles Responsive to Temperature for Heavy Oil Viscosity Reduction: Synthesis, Characterization, and Performance

“…In the high-resolution TEM (HR-TEM) images (Figure 5a), it was observed that the spacing of two adjacent lattice faces in a specific direction was 0.21, 0.25, and 0.3 nm, corresponding to the lattice spacing of (400), (311), and (220) faces of cubic magnetite, respectively. 51 The crystal phase was further confirmed by SAED (Figure 5b) and XRD images (Figure 6a). For magnetic nanoparticles, there were six diffraction peaks located at 30.1, 35.4, 43.1, 53.6, 57.2, and 62.7°, corresponding to (220), (311), (400), (422), (511), and (440) 9 planes of the cubic spinel structure, respectively.…”

“…Figure a,b shows that the aggregation of CN-NPs was significantly reduced compared with unmodified Fe 3 O 4 nanoparticles. In the high-resolution TEM (HR-TEM) images (Figure a), it was observed that the spacing of two adjacent lattice faces in a specific direction was 0.21, 0.25, and 0.3 nm, corresponding to the lattice spacing of (400), (311), and (220) faces of cubic magnetite, respectively …”

Extraction of gamma iron oxide (γ-Fe2O3) nanoparticles from waste can: Structure, morphology and magnetic properties

“…The primary purpose of this invention is to recover metal values from iron-containing waste materials and convert them to magnetic γ-Fe 2 O 3 nanoparticles having a wide range of applications from catalysis to waste management [ 9 , 10 ]. It is widely used for the production of, e.g., magnetic materials [ [11] , [12] , [13] ], sensing materials [ 14 ], pigments [ 15 ], sorbents [ 16 , 17 ], photocatalysts [ 16 ], storing data [ 18 ], for biomedical applications such as drug delivery [ 19 , 20 ], contrast agents for resonance imaging [ [21] , [22] , [23] ] and hyperthermia treatment [ 18 , 24 ], as well as being key components for adsorption and storage purposes [ 25 , 26 ]. Recently, iron oxides have been used in a huge amount as electrodes for sodium-ion, lithium-ion, and alkaline-ion batteries [ [27] , [28] , [29] , [30] , [31] ].…”