Preparation of Fe 3 O 4 nanoparticles modified with n-dodecylphosphonic acid via a one-pot nonaqueous process using an oxidation reaction of tetrachloroferrate (III) anions by pyridine-N-oxide

Atsuo Kamura, Masahiko Ozaki, Naokazu Idota, Yoshiyuki Sugahara

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Magnetite (Fe 3 O 4 ) nanoparticles (NPs) modified with n-dodecylphosphonic acid (DDPA) were prepared by one-pot nonaqueous synthesis using a salt comprising tetrachloroferrate (III) anions and methyltrioctylammonium cations as an Fe source, n-octylamine as a reductant, pyridine-N-oxide as an oxygen donor and DDPA as a phosphorus coupling reagent. The X-ray diffraction patterns, X-ray photoelectron spectroscopy and high-resolution transmission electron microscope (HRTEM) observation showed the formation of Fe 3 O 4 NPs when the amount of DDPA was small (DDPA/Fe < 1/16). Thermogravimetry and infrared spectroscopy demonstrated surface modification of Fe 3 O 4 NPs with DDPA. TEM observation showed the size range of Fe 3 O 4 NPs to be 2–10 nm. Dynamic light scattering analysis showed narrow particle size distribution of Fe 3 O 4 NPs in toluene, moreover, with median diameters of 9.1 (DDPA1/32) and 16 nm (DDPA1/64). Magnetic characterization of Fe 3 O 4 NPs modified with DDPA showed lower saturation magnetization as compared with unmodified Fe 3 O 4 NPs, and indicated superparamagnetic Fe 3 O 4 NPs formation.

Original languageEnglish
JournalMaterials Research Bulletin
Publication statusPublished - 2019 Jan 1



  • A. Magnetic materials
  • A. Nanostructures
  • B. Chemical synthesis
  • B. Magnetic properties

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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