Morphology-Controlled Synthesis of Magnetites with Nanoporous Structures and Excellent Magnetic Properties

Abstract

Different morphological single-crystal magnetites (Fe 3 O 4 ) with a nanoporous structure, which exhibit excellent magnetic properties, have been synthesized by a polyol process. Both the type of polyol and the concentration of KOH play important roles in the formation of various morphologies. Cubic, truncatedoctahedral, and octahedral shapes can be prepared by changing the concentration of the KOH solution in ethylene glycol. Sequentially, a series of submicro magnetites have been successfully obtained in the shape of spheres, truncated cubes, and equilateral octahedra by incrementally adjusting the concentration of KOH in glycerol. All the samples are ferromagnetic at 2 K but nearly paramagnetic at 300 K except the cubic sample. These Fe 3 O 4 crystals may have a potential application as magnetic carriers for drug targeting because of their excellent soft-magnetic properties.

Iron oxide surfaces

“…It is interesting to note that a similar motif underlies the SCV reconstruction at the Fe 3 O 4 (100) surface [35] (see section 3.3.3). The most common occurrences of this compound are in the Earth's lower mantle [192] [196] (see Figure 21). The authors suggest that high levels of KOH lead to the adsorption of OH anions on certain planes.…”

Controlled Magnetic Properties of Iron Oxide-Based Nanoparticles for Smart Therapy

“…The water-soluble magnetite nanoparticles could be prepared under similar reaction conditions with addition of α,ω-dicarboxyl-terminated poly(ethylene glycol) as a surface capping agent . Zhao et al (2008) reported the formation of nanoporous Fe 3 O 4 particles with excellent magnetic properties and various specific morphologies by simply changing the solvent system and amount of KOH. In a typical process, the FeSO 4 was dissolved in ethylene glycol or glycerol to form a homogeneous solution, followed by a quick addition of KOH at room temperature.…”

Shape-Evolution and Growth Mechanism of Fe3O4Polyhedrons

“…According to many reports in the literatures [16,17], the pH value has a great effect on the formation of Fe 3 O 4 polyhedrons. To verify this claim, different conditions were implemented with NaOH additions of 2.0 mmol, 3.75 mmol, 5.0 mmol, and 12.5 mmol with a fixed dosage of hydrazine hydrate (1.5 mL).…”

“…As a FCC crystal, a general sequence of surface energies may hold, {111} < {100} < {110}, which indicates that the Fe 3 O 4 crystals usually exist with {111} lattice planes as the basal surfaces [16]. The difference in , the growth rate in ⟨100⟩ to that of ⟨111⟩, results in a series of polyhedral shapes; however, the factors controlling this difference remain controversial.…”

“…Zhang [21]. Most of the views indicate that the pH value of the precursor solution is the key factor affecting the morphologies of the products [16]. Therefore, it remains necessary to systematically study the shape-evolution process and determine the underlying shape-evolution mechanisms for Fe 3 O 4 particles.…”