Synthesis, Microstructure And Magnetic Properties Of Fe-SiO₂ Nanocomposite Materials

The interest in nanocomposites consisting Of magnetic ultra-fine or nanosized particles embedded in an immiscible insulating non-magnetic matrix has grown considerably in recent years.Prepared the Fe-SiO₂ nanocomposite material by the HEBM sucssefully,They can be used in the area of electronic cell,electronic design wave absorbing materials and so on.In this article,we prepared the Fe_x(SiO₂)_1-xserial nanocomposite material by the HEBM with Fe volume fraction X in the range 0.2≤X≤0.9.The ratio of the weight of the balls to that of the powder was 20:1,milling rate was 240 rpm,milling time is 10 to 80 hours.we use the Ar in order to prevent the Fe from being oxided.The results of XRD and TEM for the samples milled for 40 h indicate the part of particles agglomerate.Using HF acid eroding the samples,the morphology of sample is nearly spherical Fe(5-15nm)particles embedded in SiO₂ matrix.The results of XRD also indicate that Fe grains with a bcc structure.The average grain size is 12nm..In tiffs study,the effect of milling time,processing control agent(PCA)and different rotation of main disk on the grain size was also studied.The results reveal that the average grain size abruptly decreasing with the milling time at the beginning of milling.After milled for 60h,the average grain size approach to a saturated value(about 12nm)and this grain size is unchanged with increasing the milling time.The PCA,milling rate also have great effect on the grain size.The coercivity of samples is relation to the Fe content and milling time,changing from 40 Oe to 400 Oe.The coercivity of samples increase with the increasing the milling time whereas the coercivity of samples decrease with the increasing the Fe content at the same milling time.