Mullite-type Bi2Mn4O10 thin films prepared by a PVA-assisted sol–gel method

Abstract

Mullite-type Bi2Mn4O10 is an attractive material for several potential applications, such as energy conversion and storage, data storage, batteries and photoelectrochemical devices. Bi2Mn4O10 thin films were prepared by sol–gel from a simple and highly stable precursor solution, based on the corresponding metal nitrate salts, acetic acid and polyvinyl alcohol. The films were deposited by dip-coating onto FTO substrates and dried at 350 °C; the dipping-drying cycle was repeated six times and the films were finally sintered at 600 °C. The films were characterized using GIXRD, revealing an excellent match with the ICDD database and previous studies. The UV–Vis measurements showed a direct band gap of 1.78 eV for the films. Raman spectroscopy permitted the identification of the Ag, B1g and B2g vibrational modes. The electrical properties via Hall effect measurements showed that the Bi2Mn4O10 thin films exhibit an n-type semiconductor behavior. Finally, the FESEM micrographs and AFM images revealed homogeneous, nanostructured thin films. In summary, through this comprehensive characterization, it was observed that high quality, nanocrystalline semiconductor thin films of Bi2Mn4O10 can be produced using this simple sol–gel method.