Mechanochemical synthesis and characterization of nanodimensional iron–cobalt spinel oxides

Iron–cobalt spinel oxide nanoparticles, CoxFe3−xO4 (x = 1, 2), of sizes below 10 nm have been prepared by combining chemical precipitation with high-energy ball milling. For comparison, their analogues obtained by thermal synthesis have also been studied. The phase composition and structural properties of the obtained materials have been investigated by means of X-ray diffraction, Mössbauer spectroscopy, infrared spectroscopy, temperature-programmed reduction and magnetization measurements. X-ray diffraction shows that after 1 h of mechanical treatment ferrites are formed. The measurement techniques employed indicate that longer milling induces an increase in crystal size while crystal defects decrease with treatment time. Magnetization and reduction properties are affected by the particles size, the iron/cobalt ratio and the synthesis conditions.