Structure and Magnetic Properties of Nanopowders of Iron Oxides and Hybrid Nanopowders of the Core-Shell Type Based on Them.

Autor: Grebennikov, I. S., Savchenko, A. G., Zaytseva, M. P., Muradova, A. G., Yurtov, E. V.
Zdroj: Bulletin of the Russian Academy of Sciences: Physics; Sep2018, Vol. 82 Issue 9, p1222-1231, 10p
Abstrakt: 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+[Fe1-3 x2+Fe1+2 x3+Vx]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. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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