Cobalt modified iron oxides: dependence of surface topography on preparation method and resulting influence on magnetic properties

Depending on which method of synthesis is adopted for the deposition of a cobalt ferrite layer on gamma -Fe/sub 2/O/sub 3/ particles, very different surface topographies of the modified particles are observed in electron micrographs. The modifying layers are either grown as smooth epitaxially crystallized films or as a coating of more or less isolated ferrite particles. In the later case, significantly lower H/sub c/-enhancements after modification are observed. The layer is still magnetically strongly interacting with the core particle of gamma -Fe/sub 2/O/sub 3/. To explain the results, differences in magnetostatic energy as a function of surface topography are discussed.<
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