Exchange bias in plasma-sprayed MnZn ferrite

The antiferromagnetic phase FeO (wustite) forms in plasma-sprayed MnZn ferrites from pure spinel phase powder. An exchange bias is observed in hysteresis loops of both ferrite coatings and single splats; the exchange bias decreases and disappears with annealing. X-ray diffraction indicates that the wustite FeO changes to hematite Fe/sub 2/O/sub 3/ upon annealing. Annealing -induced cation ordering and diffusion influence the ferrite magnetic properties by increasing the saturation magnetization and decreasing the coercivity.