The cooling rate dependence of cation distributions in CoFe2O4

The room-temperature cation distributions in bulk CoFe2O4 samples, cooled at rates between <10−2 and ∼103 °C s−1, have been determined using Mössbauer spectroscopy in an 80-kOe magnetic field. With increasing cooling rate, the quenched structure departs increasingly from the mostly ordered cation distribution ordinarily observed at room temperature. However, the cation disorder appears to saturate just short of a random distribution at very high cooling rates. These results are interpreted in terms of a simple relaxation model of cation redistribution kinetics. The disordered cation distributions should lead to increased magnetization and decreased coercivity in CoFe2O4.