The magnetic properties of CNTs/Fe3O4 hybrid materials were investigated at room temperature using a vibrating sample magnetometer with an applied field of 6000 OerHr6000 Oe. Fig. 5 shows the hysteresis loops of the samples, which are the typical loops of a soft magnet. Coercivity and saturation magnetization values for all samples are listed in Table 1. The coercivity of CNTs/Fe3O4 hybrid materials increased with the increasing weight ratio of FeCl3 6H2O to CNTs; this trend can be well correlated with the size of the Fe3O4 nanoparticles, i.e. the size of the nanoparticles increased with the increasing weight ratio of FeCl3 6H2O to CNTs. The dependence of the saturation magnetization of the CNTs/Fe3O4
hybrid materials at room temperature is shown in Table 1. The saturation magnetization values of the materials are 13.84, 35.47 and 60.94 emu g1 with the increasing weight ratio of FeCl3 6H2O to CNTs.