Journal of Materials Science

, Volume 44, Issue 3, pp 926–930 | Cite as

Preparation of γ-Fe2O3 nanopowders by direct thermal decomposition of Fe-urea complex: reaction mechanism and magnetic properties

  • S. Zhao
  • H. Y. Wu
  • L. Song
  • O. Tegus
  • S. Asuha


In this work, a novel method of producing maghemite (γ-Fe2O3) nanopowders has been developed, which can be performed by the direct thermal decomposition of an Fe–urea complex ([Fe(CON2H4)6](NO3)3) in a single step. The reaction mechanism, particle morphology, and the magnetic properties of the γ-Fe2O3 nanopowders have been studied by using thermogravimetric (TG), differential scanning calorimetry (DSC), fourier transformed infrared (FTIR) spectroscopy, elemental analysis, X-ray powder diffraction (XRD), transmission electron micrograph (TEM) observations, and magnetic measurements. Thermal analyses together with the results of XRD show that the formation of γ-Fe2O3 occurs at ~200 °C through a two-stage thermal decomposition of the [Fe(CON2H4)6](NO3)3 complex. The resulting iron oxide phases (i.e., γ-Fe2O3 and α-Fe2O3) are strongly dependent on the synthesis conditions of the [Fe(CON2H4)6](NO3)3. When the molar ratio of Fe(NO3)3 · 9H2O to CON2H4 that is used for the synthesis of [Fe(CON2H4)6](NO3)3 is 1:6 (i.e., molar ratio in stoichiometry), a mixed phase of γ-Fe2O3 and α-Fe2O3 is formed. When the molar ratio is 1:6.2 (i.e., using an excess CON2H4), on the other hand, a pure γ-Fe2O3 is obtained. Magnetic measurements show that resulting nanopowders exhibit a ferromagnetic characteristic and their maximum saturation magnetization increases from 47.2 to 67.4 emu/g with an increase in the molar ratio of Fe(NO3)3 · 9H2O to CON2H4 from 1:6 to 1:6.2.


Differential Scanning Calorimetry Transmission Electron Micrograph Total Weight Loss JCPDS File Ferric Nitrate 


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Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • S. Zhao
    • 1
  • H. Y. Wu
    • 1
  • L. Song
    • 2
  • O. Tegus
    • 2
  • S. Asuha
    • 1
  1. 1.Chemistry & Environment Science CollegeInner Mongolia Normal University, Key Laboratory of Physics and Chemistry of Function MaterialsHohhotChina
  2. 2.Physics & Electronic Information CollegeInner Mongolia Normal University, Key Laboratory of Physics and Chemistry of Function MaterialsHohhotChina

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