Atomic structure and magnetic properties of MnFe{sub 2}O{sub 4} nanoparticles produced by reverse micelle synthesis
- Advanced Materials Research Institute, University of New Orleans, New Orleans, Louisiana 70148 (United States)
- U.S. Naval Research Laboratory, Washington, DC 20375-5000 (United States)
Using the aqueous cores of reverse micelles as nanoreactors, nanoparticles (d{approximately}10&hthinsp;nm) of the mixed ferrite MnFe{sub 2}O{sub 4} were produced. Seven processing trials were performed where the concentration of ammonium hydroxide, reaction temperature, and the oxidizing agent were varied. All trials result in Mn-ferrite particles with varying chemistry and structure. The Mn concentration in the resulting ferrite is strongly enhanced by both the presence of H{sub 2}O{sub 2} as an oxidizing agent and a surplus of ammonium hydroxide. The increased Mn concentration correlates with a higher fraction of octahedrally coordinated Mn cations. When near-stoic amounts of ammonium hydroxide are used, the resulting ferrites are nearly stoichiometric with a more equitable distribution of Mn cations on the octahedral and tetrahedral sublattices. In all ferrite nanoparticles, the Mn cations have a preference for octahedral site occupancy that is larger than the 20{percent} measured in bulk Mn-ferrite. We attribute the cation filling trends to the stabilization of excess trivalent Mn during processing. {copyright} {ital 1999 American Institute of Physics.}
- OSTI ID:
- 353688
- Journal Information:
- Journal of Applied Physics, Vol. 85, Issue 8; Other Information: PBD: Apr 1999
- Country of Publication:
- United States
- Language:
- English
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