Abstract

The oxide system, (Fe 2O 3) x(Al 2O 3) y(SiO) 1-x-y (x=33.3−50.0; y=20.0−40.0) with spinel type structure has been prepared, and its crystallographic and magnetic properties has been investigated with X-ray and Mössbauer effect methods. The crystal structure of the system is found to be a cubic spinel type. The lattice parameters increase with increasing Fe 2O 3 concentration, while the influence of Al 2O 3 substitution for SiO is small. The Mössbauer spectra which show broad quadrupole doublets at x=33.3, 43.7 and y=33.3, 21.8 change into the complex Zeeman patterns when x=50.0 and y=20.0, 30.0 and 40.0. Also the partly existing ferrous states of iron ions change into the ferric states. In the Zeeman sextets, the magnetic hyperfine fields and Néel temperature increase as the Al 2O 3 content increases. These variations can be explained on the basis of increasing A-B superexchange interaction.

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