Effects of crystal size and sphere diameter on static magnetic and electromagnetic properties of monodisperse Fe3O4 microspheres

Controllable Synthesis of CuxFe3−xO4@Cu Core–Shell Hollow Spherical Chains for Broadband, Lightweight Microwave Absorption

“…[48] In this case, H c increases with crystal size. [3,5] EM properties EM parameters and their matching were studied to reveal the microwavea bsorbing mechanism of Cu x Fe 3Àx O 4 @Cu composites. As shown in Figure 7, the EM parameters are affected by the composition of all Cu x Fe 3Àx O 4 @Cu composites within 2-18 GHz.…”

“…However, the high density and low permittivity of spinelf errites limit their application as light and thin absorption materials. Light absorption materials can be prepared by using two approaches:i )decreasing the absorber density by selecting hollow or porous structures [3,4] or decreasing the particle size to nanoscale [5] and ii)improving EM parameters to reduce the filling mass or volume fraction of the absorbers in the matrix. [6] Permittivity can be enhanced with the followings trategies:i )enhancement of space charge, ori-entation, or interface polarizationsb ym odulating the dimension, morphology, composition, and structure of absorbents; [7,8] using nanomaterials with low percolation threshold to form microcurrents through an electrical percolation network; [9,10] ii) selection of plasmonic structures( i.e.,r ings) as absorbers to generate plasmonic resonance-enhanced permittivity; [11,12] and iii)surface modification of the particles using other materials with high permittivity.…”

Magnetic Sensing Potential of Fe3O4 Nanocubes Exceeds That of Fe3O4 Nanospheres

“…Previous studies have shown that the high crystallite size in nanocubes leads to high saturation magnetization because of reduced surface spin disorder. 13 , 31 , 50 Liu et al varied the crystal size and showed that for polycrystalline nanospheres less than 250 nm in size, the saturation magnetization depends on both the diameter and its crystal size (and hence crystallinity). 50 As expected, 50 , 51 owing to the higher crystal size in the multidomain MNPs, the saturation magnetization of Fe 3 O 4 nanocubes is higher than that of nanospheres ( Tables 1 – 3 ).…”

The Effect of Polyol Composition on the Structural and Magnetic Properties of Magnetite Nanoparticles for Magnetic Particle Hyperthermia

“…Generally, since the approach of wet chemistry methods is aggregation of atoms produced in solution into nanoparticles, good control of the reaction, of the size of the particles, and the size distribution may be achieved. The most widely used methods of iron oxide nanostructuring are thermal decomposition [9,10], sometimes combined with the polyol process [11,12], and solvothermal method [13,14,15,16], where polyols may also be used as well. Some of the most common precursors that have been used in iron oxide nanostructuring are iron (II) acetylacetonate [17], iron oleate [18], iron (II) acetate [19], iron nitrate nonahydrate [20], and iron pentacarbonyl [21,22].…”

“…Generally, this method offers a wide range of reaction temperature values, considering that any long-chain polyol has a different boiling point, which depends on the relative molecular mass, leading to the control of the physicochemical characteristics of the nanoparticles such as crystal phase and size. Magnetite particles in a size range between 82 and 1116 nm have been prepared by Liu et al [14] by using ethylene glycol (EG). Longer-chain polyols such as triethylene glycol (TrEG) have been used in magnetite nanostructuring [14,15] as well, while even longer polyethylene glycols (PEGs) resulted to same phase nanoproducts [15,16].…”