Synthesis and magnetic properties of magnetite-silicate nanocomposites derived from iron oxide of bacterial origin

Hideki Hashimoto, Tatsuo Fujii, Makoto Nakanishi, Yoshihiro Kusano, Yasunori Ikeda, Jun Takada

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Magnetic nanocomposites containing magnetite (Fe 3O 4) nanoparticles were prepared from iron oxide microtubules produced by Leptothrix ochracea, a species of water-habitant iron-oxidizing bacteria. The microtubules were mainly composed of Si-containing ferric hydroxide that shows a broad X-ray diffraction pattern similar to that of 2-line ferrihydrite. After moderate heat treatment in a reductive atmosphere above 325 °C, the ferric ions were partially reduced to a ferrous state, and nanocrystalline Fe 3O 4 with a spinel-type structure was formed in a noncrystalline silicate matrix. The average crystallite size of the Fe 3O 4 nanoparticles was estimated to be in the order of a few nanometers. The sample heat-treated at 500 °C exhibited considerable magnetization together with superparamagnetic behavior at room temperature, and super-spin-glass interaction occurred at low temperature. On further heat treatment above 530 °C, Fe 3O 4 was reduced to wüstite (Fe 1 -xO) and finally crystallized into iron metal (α-Fe) and ferrous silicate (Fe 2SiO 4).

Original languageEnglish
Pages (from-to)1156-1161
Number of pages6
JournalMaterials Chemistry and Physics
Volume136
Issue number2-3
DOIs
Publication statusPublished - Oct 15 2012

Keywords

  • Amorphous materials
  • Heat treatment
  • Magnetic materials
  • Magnetometer (for magnetic field, susceptibility, magnetic moment, magnetisation measurements)
  • Nanostructures

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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