Recrystallisation phenomena during high energy ball milling

The structural and morphological evolution of the NiZn ferrite during mechanical activation has been investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM) and chemical analysis. During the milling process an important amount of metallic phases due to the vials and balls contaminates the ferrite powder and functions as co-participant to the mechanical activation. The XRD- spectra of the as-milled powders showed the presence of the metallic contribution up to 200 hours of milling. For longer intervals of time the extralines intensities due to the presence of metallic phases decrease and only a spinel phase is observed after 400 hours of total milling. The TEM image revealed, after 200 hours, spheroidal nanometric particles in the range 30-80 nm, alongside of some needle type particles. When the milling time was increased, some big plate monocrystals appear and grow. After 400 hour milling, polyhedral crystals 250 divided by 1000 nm size could be observed in the powder.