Structure and Magnetic Properties of Nanopowders of Iron Oxides and Hybrid Nanopowders of the Core–Shell Type Based on Themстатья
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Дата последнего поиска статьи во внешних источниках: 10 апреля 2019 г.
Аннотация:The results are presented from complex phase structural and magnetic studies for uncoated and hybrid nanopowders based on iron oxide of the core–shell type (Fe3−xO4@SiO2). Their phase and structural characteristics are determined along with their and morphologies. It is shown that the nanopowders are nonstoichiometric magnetite Fe3+[Fe2+1−3xFe3+1+2xVx]О4 in which there are volume and surface regions that differ by the electronic state of their iron ions. The results from magnetic measurements reveal a relationship between the dispersity and magnetic properties of nanopowders. The change in the thickness of a defect surface layer and its specific magnetization is analyzed quantitatively as a function of the mean size of magnetite nanoparticles and the presence of a coating. The resulting dependences are constructed and analyzed.