Magnetic properties of NiSi/SiO2 nanocomposites with core-shell structure prepared by selective oxidation

NiSi/SiO2 core-shell nanoparticles were firstly synthesized by DC arc-discharge approach and annealing process. The products were characterized by SEM, TEM, EDX, XRD and VSM. The results show that as-prepared NiSi/SiO2 core-shell nanoparticles have the diameter bettween 40-200 nm and the thickness of the SiO2 shell is about 20 nm. The growth mechanism of SiO2 shell was also explained based on the preferential oxidation, crystallographic and thermodynamic theory. The as-prepared NiSi/SiO2 core-shell nanoparticles exhibit superparamagnetism at room temperature.