Temperature Dependence of Cation Distribution and Oxidation State in Magnetic Mn−Fe Ferrite Nanocrystals

• DOI: 10.1021/ja973085l
• Publication Date: 2002-07-26T05:21:43Z
• Authors: Z. John Zhang; Zhong L. Wang; Bryan C. Chakoumakos; Jin S. Yin
• Keywords: Oxidation state; Coprecipitation

The magnetic properties of spinel nanoparticles are determined by crystal chemistry issues such as cation distribution and oxidation states. state Mn−Fe have been systematically studied at various temperatures using neutron diffraction electron energy loss spectroscopy, respectively. prepared coprecipitation a high degree inversion with 61% the tetrahedral sites occupied Fe3+ cations. correlates expected from random occupancy cations consisting Fe (60%) Mn (40%). After heat treatment in vacuum, reaches an equilibrium 29% inversion. Initially, one-half +3 other half +2 state. Mn3+ slowly irreversibly reduced to Mn2+ increasing temperature. When temperature approaches 600 °C, all These results provide direct evidence for temperature-dependent change nanoparticles, which has closely related controversy on attributing changes crystallite size effect. will also understanding how control order these nanoparticles.