Nonaqueous synthesis of magnetite nanoparticles via oxidation of tetrachloroferrate anions by pyridine-N-oxide

Atsuo Kamura, Naokazu Idota, Yoshiyuki Sugahara

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Fe3O4 nanoparticles were prepared from a salt comprising a tetrachloroferrate anion and a methyltrioctylammonium cation in toluene using ethylenediamine as a reductant and pyridine-N-oxide as an oxygen donor and an oxidant. The X-ray diffraction (XRD)analysis, X-ray photoelectron spectroscopy (XPS)and Raman spectroscopy showed that the product was Fe3O4. Water content measurement with a Karl Fischer moisture meter showed the presence of only a small amount of water in the present system, indicating a limited contribution of water to the formation of Fe3O4 nanoparticles. The Fe3O4 nanoparticle size based on transmission electron microscopy (TEM)observation was approximately 10–30 nm, a result consistent with the crystallite diameter estimated by Scherrer's equation (15.7 nm). A possible reaction mechanism involves the reduction of Fe3+ to Fe2+ by ethylenediamine, coordination of both ethylenediamine and pyridine-N-oxide to Fe2+, and oxidation of a part of Fe2+, leading to a mixed-valence iron-oxygen network, which was a precursor of Fe3O4 nanoparticles. As concerns magnetic properties, saturation magnetization of the product was 57 emu g−1. Both the coercivity and remanent magnetization were nearly zero and the similar decreases in magnetization were observed above the blocking temperature in the zero-field-cooled and field-cooled curves, results indicating the formation of superparamagnetic Fe3O4 nanoparticles.

Original languageEnglish
Pages (from-to)81-88
Number of pages8
JournalSolid State Sciences
Volume92
DOIs
Publication statusPublished - 2019 Jun

Keywords

  • Magnetite
  • Nanoparticles
  • Nonaqueous synthesis
  • Pyridine-N-oxide
  • Superparamagnetism

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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