THE MAGNETIC BEHAVIOUR OF BARIUM FERRITE PREPARED BY GLASS CRYSTALLIZATION METHOD

Barium ferrite has been prepared by the glass crystallization method at annealing temperatures Ta up to 1000 °C. The investigation is concentrated on the annealing temperature region in which the magnetic M-phase dominates. In addition to the data obtained from static hysteresis loops we determined the anisotropy field from microwave measurements. One result is that three annealing temperature regions must be distinguished. In the first region (Ta ≤ 600 °C) thermal agitation influences the magnetic properties. Above this temperature the crystals achieve very good hard magnetic properties (e.g. HcJ=488 kA/m at Ta=800 °C). The effective anisotropy field H'A here mainly is a function of the crystal shape. With further increasing temperatures the crystals change into the multidomain state