Synthesis of magnetic nanoparticles by low-energy dual ion implantation of iron and nickel into silicon dioxide followed by electron beam annealing

Magnetic nanoparticles have been made by low-energy dual ion implantation of iron and nickel into SiO2 with a nickel fluence ratio of 82% followed by electron beam annealing for 1800 s at 1000 degrees C. After annealing, there is significant diffusion of iron and nickel into the silicon dioxide layer. Annealing also led to the formation of superparamagnetic nanoparticles with a narrow particle size distribution. The saturation moment at 5 K was 0.7 mu(B) and a similar value was observed at 300 K, which indicates that the Curie temperature is far above room temperature. This moment is lower than that expected for Ni0.82Fe0.18. While the results clearly show the formation of superparamagnetic nanoparticles, it is not possible to determine whether nickel-iron, iron or nickel has formed.