A Mössbauer and X-ray diffraction study on the cation distribution in FeAl₂O₄

The Mössbauer spectrum of FeAl₂O₄ consists of three absorption peaks at 0, 1.46 and 2.56 mm s^-1 relative to a ⁵⁷Co/Cu source. The spectrum can be resolved into two quadrupole-split spectra. The outer pair of lines corresponds to a quadrupole splitting of 2.76±0.10 mm s^-1 and an isomer shift of 1.52±0.10 mm s^-1 and may be attributed to the Fe²⁺ ions at the B sites. The inner doublet with a quadrupole splitting of 1.39±0.10 mm s^-1 and an isomer shift of 1.10±0.10 mm s^-1 can be attributed to the Fe²⁺ ions at the A sites. The degree of inversion x was determined from the relative areas under the two spectra to be 23±2%. This is in agreement with the value of 25% determined from the intensities of the X-ray diffraction powder pattern.