Abstract:
Fine particles of ferrimagnetic MgFe2O4 were synthesized through a sol-gel supercritical drying procedure, then cold-pressed and heated at 500 and 800?°C. These materials were characterized by Mössbauer spectrometry in the temperature range 25 298 K, and in the presence of a small applied magnetic field. The Mössbauer measurements show that heat treatment results in the formation of a small percentage of a-Fe2O3, an increase in the mean particle size and hyperfine magnetic field, and a decrease in the inversion parameter of the magnesioferrite. An average anisotropy constant equivalent to the bulk magnetocrystalline anisotropy is estimated for particles with diameter D=14 nm.