Preparation and characterization of CoFe2O4 powders and films via the sol–gel method

► We prepared the CFO materials via two sol-gel methods by selecting different chelators. ► We prepared CFO films using the CFO precursor solutions prepared by the better method. ► The CFO films with nano-scaled film thicknesses have good morphologies, clear layered structure and better magnetic properties than the CFO powders. The CoFe2O4 (CFO) starting precursor solutions were prepared by two sol–gel methods. The XRD results show that the second sol–gel method is a better method to obtain CFO materials with high purity. The CFO precursor solutions prepared by the second sol–gel method were spin-coated onto the Pt/Ti/SiO2/Si substrate to obtain CFO films. With the increase of annealing temperature, the relative amounts of secondary phases in CFO films are decreased. When annealed at 700°C, CFO films are almost composed of the main phase and the substrate phase without secondary phases. The CFO film is crack-free and has compact structure without any pore. The thickness of CFO film is about 49nm. The starting precursor solution with the concentration of 0.15molL−1 is better for preparing CFO films. The CFO films with nano-scaled film thicknesses have better magnetic properties than the CFO powders.