Alkaline Metal Reagent-Assisted Synthesis of Monodisperse Iron Oxide Nanostructures

Abstract

Abstract:The solvothermal decomposition of iron complexes using the heat-up process enables monodisperse Fe 3 O 4 nanoparticle synthesis. Here, we demonstrate that the high reduction potential capability of alkaline metal reagents in the reductive environment allows for pure magnetite phase formation at 200 • C, which is lower than that of typical synthetic method and offers highly crystalline superparamagnetic and ferrimagnetic nanostructures with the ability to control uniformity including spherical and cubic morphology with narrow size distributions. Our method involved reduction of the acetylacetonate and acetate anions to aldehyde and alcohol as an oxygen resource for iron oxide nucleation in an inert condition. For confirming the developed pure surface phase of alkaline metal reagent-assisted magnetite nanoparticle, the magnetic field-dependent shifting of blocking temperature was investigated. The degree of the exchange interaction between core spins and disordered surface spins is attributed to the ratio of core spins and disordered surface spins. The decrease in disordered surface spins deviation due to an enhanced pure phase of magnetite nanoparticles exhibited the negligible shift of the blocking temperature under differently applied external field, and it demonstrated that alkaline metal reagent-induced reductive conditions enable less formation of both disordered surface spins and biphasic nanostructures.

Fe3O4 Nanoparticles: Structures, Synthesis, Magnetic Properties, Surface Functionalization, and Emerging Applications

“…Thermal decomposition of iron complexes at high temperature in high-boiling point organic solvents has proven to be an effective method to generate Fe 3 O 4 nanospheres with sizes ranging from 4 to 30 nm [54][55][56][57][58]. Sun et al reported the thermal decomposition of Fe(acac) 3 in phenyl ether (boiling point: 260 • C) at 265 • C to synthesize monodisperse 4 nm Fe 3 O 4 SNPs [54].…”

“…Therefore, precisely controlling the temperature of the reaction and a powerful heating process represent a technical challenge for large-scale production. Later, Lee and coworkers successfully lowered the reflux temperature to 200 • C using alkaline metal reagents to assist with the reduction of iron precursors [58]. In the presence of Mg(acetate) 2 , monodisperse Fe 3 O 4 SNPs with sizes of 8, 11, 15, and 18 nm were prepared.…”

“…Lee and collaborators reported the synthesis of magnetite nanocubes with sizes of 22, 36, and 57 nm at a lower refluxing temperature (200 • C) using an alkaline metal acetate to assist with the reduction process [58]. The amount of sodium oleate surfactant was found to play an important role in controlling the size of nanocubes.…”

Magnetic Nanomaterials for Magnetically-Aided Drug Delivery and Hyperthermia

“…The main obstacle of this procedure is the control of nanoparticle size and polydispersity. One of the major advantages is the opportunity to synthesize composite materials [72][73][74][75]. While normal micelles form in an aqueous medium, reverse micelles form in hydrophobic media [68,70].…”

Synthesis and Properties of Bulk Nanostructured Metallic Materials

“…According to their results, Nb 2 O 5 synthesized though the sol-gel method had orthorhombic symmetry and exhibited high pressure stability. Lee et al [10] demonstrated a facile method to synthesize enhanced pure phase and monodisperse magnetite nanoparticles and nanocubes. The high reduction potential capability of alkaline metal reagents in the reductive environment allowed formation of a pure magnetite phase.…”