Synthesis and characterization of barium ferrite–silica nanocomposites

Abstract

In this work, we prepared barium ferrite-silica (BaM-SiO2) nanocomposites of different molar ratios by high-energy ball milling, followed by heat-treatment at different temperatures. The microstructure, morphology and magnetic properties were characterized for different synthesis conditions by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). The results indicate that 15h of milling was enough to avoid the generation of hematite phase and to get a good dispersion of barium ferrite particles in the ceramic matrix. For milling periods beyond 15h and heat treatment above 900°C, the XRD patterns showed the presence of hematite phase caused by the decomposition of BaM. The agglomerate size observed through SEM analysis was around 150nm with a good BaM dispersion into the SiO2 matrix. The highest saturation magnetization (Ms) value obtained was 43emu/g and the corresponding coercivity (Hc) value of 3.4kOe for the composition 60BaM-40SiO2 milled for 15h and heat treated at 900°C. This coercivity value is acceptable for the application in magnetic recording media.