Exploring the one-step synthesis of composite BiFeO3 based coatings

Abstract A one-step, annealing-free, and rapid aerosol assisted CVD method was used for the growth of composite BiFeO3 coatings. Through this method, an area of approximately 19 cm2 was coated in 7.5 min. Microstructural characterization by X-ray diffraction, Raman spectroscopy, and electron microscopy proved that BiFeO3 can be deposited onto amorphous and crystalline substrates. According to X-ray diffraction and Raman spectroscopy, small amounts of binary oxides of Bi and Fe were found in the samples; however, a more homogeneous BiFeO3 single phase was achieved using TiO2 coated borosilicate glass substrates. The samples exhibited a composite microstructure, which consisted of a thin layer of BiFeO3 (around 70 nm thick) covered by truncated and porous spherical particles of BiFeO3, Bi2O3, and Fe2O3 of several hundreds of nanometers of diameter. Findings suggested a rapid transformation of the precursor solution aerosols while traveling towards the substrate, which due to differences in size and volume, provoked variations in the composition and the development of irregular morphologies. Although the samples exhibited rough surfaces, the porous coatings offer the possibility of having materials with high-surface areas supported on inert substrates, which are attractive for applications involving surface reactions, such as photocatalysis or ambient remediation. The direct band gap of the samples exhibited values of 2.1 and 2.45 eV, reinforcing the feasible use of these materials in applications that could be triggered upon absorption of visible light.