Synthesis of mono-disperse hollow nickel spheres with a double shell structure using poly(methyl methacrylate) as a template

Mono-disperse hollow SiO2/Ni magnetic spheres were successfully manufactured by radiofrequency magnetron sputtering and sol–gel methods using poly(methyl methacrylate) spheres as template. After removing core templates, the hollow structure of the SiO2/Ni magnetic spheres was characterized by electron microscopy and the magnetic properties were measured by vibrating sample magnetometry. Finally, the anti-oxidation test shows that the inert SiO2 layer can protect the hollow nickel spheres from oxidization in the air very well.