Synthesis under high pressure and characterisation by Mössbauer spectroscopy of non-stoichiometric Ca2Fe2O5.12
Abstract
The calcium iron oxide Ca2Fe2O5 which contains alternate layers of iron–oxygen octahedra and tetrahedra has been found to take up additional oxygen under high pressure and elevated temperature. The Mössbauer spectra in the range 4.2–290 K establish that all the original material has been transformed into a new phase which is still structurally related to the original lattice, but features a disordered introduction of oxygen into the tetrahedral layers and oxidation of some of the iron to the +4 oxidation state. At least six distinct iron sites can be identified, and the coordination numbers established. The structural relationship of these sites and the magnetic characteristics are discussed.
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