High Temperature Behaviour of Hercynite
AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Department of Ceramics and Refractories 30-059 Kraków/Poland
Revision 29.08.2018, 26.09.2018
Volume 11, Issue 1, Pages 68 - 76
Hercynite (FeAl2O4) was obtained by Arc Plasma Synthesis (APS) and thermally annealed at 1000 °C for 1, 24 and 36 h respectively, in air. The XRD measurements, that were conducted before and after the annealing, showed an evident alteration of the original hercynite under the infuence of temperature and oxygen access. About half of the original hercynite was preserved after the longest annealing treatment of 36 h. The remained iron-aluminium spinel underwent decomposition into a few iron and aluminium oxide phases, among which non-stoichiometric magnetite and corundum were the most signifcant. Mössbauer spectroscopy showed that hercynite is a normal spinel with a slight inversion parameter of 11 %, which was increased up to 34 % after the 36 h thermal annealing. An overlapping of refexes for spinel-like phases γ-Fe2O3 and γ-Al2O3 with Fe–Al spinel interfered with their detection by X-ray diffractometry.
hercynite, FeAl2O4, spinel, structure
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