Influence of Magnetite Nanoparticles Shape and Spontaneous Surface Oxidation on the Electron Transport Mechanism

Abstract

The spontaneous oxidation of a magnetite surface and shape design are major aspects of synthesizing various nanostructures with unique magnetic and electrical properties, catalytic activity, and biocompatibility. In this article, the roles of different organic modifiers on the shape and formation of an oxidized layer composed of maghemite were discussed and described in the context of magnetic and electrical properties. It was confirmed that Fe3O4 nanoparticles synthesized in the presence of triphenylphosphine could be characterized by cuboidal shape, a relatively low average particle size (9.6 ± 2.0 nm), and high saturation magnetization equal to 55.2 emu/g. Furthermore, it has been confirmed that low-frequency conductivity and dielectric properties are related to surface disordering and oxidation. The electric energy storage possibility increased for nanoparticles with a disordered and oxidized surface, whereas the dielectric losses in these particles were strongly related to their size. The cuboidal magnetite nanoparticles synthesized in the presence of triphenylphosphine had an ultrahigh electrical conductivity (1.02 × 10−4 S/cm at 10 Hz) in comparison to the spherical ones. At higher temperatures, the maghemite content altered the behavior of electrons. The electrical conductivity can be described by correlated barrier hopping or overlapping large polaron tunneling. Interestingly, the activation energies of electrons transport by the surface were similar for all the analyzed nanoparticles in low- and high-temperature ranges.

Magnetic nanocellulose: influence of structural features on conductivity and magnetic properties

“…The electron transport mechanism of Fe3O4 shows different behaviour in different temperature regions, followed by the structural changes in the spinel system. These mechanisms are based on the polaron transport in the magnetite structure, from the tetrahedral sites (A-sites), occupied by Fe 3+ ions to the octahedral sites (B-sites), occupied by Fe 3+ and Fe 2+ ions [17,18]. Radon et al [17], claim that the nanoparticles are associated with mechanisms described by associated barrier hopping and non-overlapping small polaron tunnelling models.…”

“…These mechanisms are based on the polaron transport in the magnetite structure, from the tetrahedral sites (A-sites), occupied by Fe 3+ ions to the octahedral sites (B-sites), occupied by Fe 3+ and Fe 2+ ions [17,18]. Radon et al [17], claim that the nanoparticles are associated with mechanisms described by associated barrier hopping and non-overlapping small polaron tunnelling models. As noted by the same researchers, the AC conductivity in Fe3O4 follows Jonscher's power law, which is characteristic of disordered solids [19].…”

Influence of oleic acid coating on the magnetic susceptibility and Fenton reaction-mediated ROS generation by the iron oxide nanoparticles

“…This shift was mainly due to the movement of iron ions into the tetrahedral sites [33]. The small shoulder band at around 630 cm −1 that is visible in the FT-IR spectrum of pristine IONPs indicates the presence of maghemite [34]. However, this particular band was either very weak or not visible in the case of the FT-IR spectra of OA-IONPs.…”

Voltage-Induced Void Formation in High-Temperature Oxide Scales of Boiler Tubes

“…Due to its mixed-valenced compound, it creates a charged imbalance in the crystal lattice, resulting in the presence of electrical conductivity. As mentioned by Radoń et al [31], an increase of temperature causes the electrical conductivity of magnetite to signi cantly enhance. This is because high thermal energy allows for a greater charge carrier, facilitating the movement of all metallic ions in it.…”