Preparation and characterization of γ-Fe_2O_3/SiO_2 magnetic nanocomposites

Adding 40-nm γ-Fe2O3 nanoparticles to TEOS gelation system, and by hydrolysis and condensation of TEOS, core-shell structural γ-Fe2O3/SiO2 magnetic nanocomposites were prepared by sol-gel process. Both γ-Fe2O3nanoparticles and γ-Fe2O3/SiO2 nanocomposites were characterized by transmission electron microscope(TEM), X-ray diffraction(XRD), Fourier transform infrared(FTIR),BET and vibrating sample magnetometer(VSM). The results show that γ-Fe2O3/SiO2 nanoparticles are cubic in shape and have an average diameter of about 70nm with coated SiO2 layer of amorphous phase. The magnetic measurements indicate that magnetic nanocomposites exhibit paramagnetic behavior with saturation magnetization of 44.78 A·m2/kg, and coverage ration of 59.1%.