BaFe12O19 fine crystals dispersed in a glassy matrix: magnetic and structural properties

A Fe2O3-BaO-B2O3-Sb2O3 flux melt was rapidly quenched at 104–105 grad/s between two rotating copper rollers to form glass ribbons. By X-ray diffraction it was observed that the obtained ribbons were essentially amorphous. The ribbons were subjected to heat treatments between 200 and 780 °C in order to induce the glass devitrification. The irreversible structure changes induced by thermal heat treatments were investigated by X-ray diffraction and by scanning electron microscopy (SEM). Fine crystals of barium ferrite with sizes ranging from 50 to 330 nm, at temperatures higher than 550 °C, were observed. The magnetic properties, in terms of the evolution of size of BaFe12O19 crystals dispersed in the glassy matrix, are discussed.