Mössbauer hyperfine spectra of dilute Fe³⁺ in synthetic MgAl₂O₄ spinel

Mössbauer effect spectra of ⁵⁷Fe diffused into powdered synthetic spinel, MgAl₂O₄, exhibit paramagnetic hyperfme structure. The iron was determined to be equally distributed between the tetrahedral and octahedral sites, with the tetrahedrally coordinated iron having a longer spin-lattice relaxation time. Analysis of the spectra taken in small applied fields between 30 and 1000 Oersted at 4.2 and 1.5 K yielded the electronic zero field splitting parameters and showed both sites to have significant departures from axial symmetry.