Microemulsion-mediated solvothermal synthesis of hollow Co-Ni ferrite nanoparticle tubes and their magnetic properties

Hollow cobalt-nickel (Co-Ni) ferrite tubes with a diameter of about 200-400 nm and a length of several micrometres were synthesised by a microemulsion-based solvothermal method in combination with calcination at 500°C. The morphologies and structures of the Co-Ni ferrite tubes and their precursors of Co/Ni/Fe composite oxalate were characterised using a transmission electron microscopy, field emission scanning electron microscopy and an X-ray diffractometer. Magnetisation measurement was carried out using a vibrating sample magnetometer at room temperature. The saturation, magnetisation and coercivity of Co_0.5Ni_0.5Fe₂O₄ nanoparticle tubes could reach 19.645 emu/g and 722.35 Oe, respectively. Therefore Co-Ni ferrite tubes could be easily prepared using this method and might be applied as catalysts, magnetic materials and microwave absorbers.