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

Highlights: ► 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. - Abstract: 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 49 nm. The starting precursor solution with the concentration of 0.15 mol L−1 is better for preparing CFO films. The CFO films with nano-scaled film thicknesses have better magnetic properties than the CFO powders.