Ni-Zn ferrite nanoparticles prepared by ball milling

Samples consisting of Ni0.8Zn0.2Fe2O4 nanoparticles, both interconnected or dispersed in a matrix, were prepared by high energy ball milling, starting from bulk material previously synthesised by the conventional ceramic method at 1250 degrees C under O-2 flux. Samples with different grain size were performed. The as-milled samples were characterised by chemical analysis, X-ray diffraction and transmission electron microscopy (TEM). The nondispersed samples consist of grains with a mean size of 100 nm and a large size distribution. The dispersed powder in silica shows individual particles almost spherical with size ranging from 8 up to 50 nm. A good agreement was obtained between X-ray and TEM results. Because the as-milled powder showed after 200 hours of milling a high impurity degree, due to the stainless steel vial and balls, an original method was used to separate the phases. Magnetic measurements and Mossbauer spectra were performed.