Precursor-based bismuth ferrite ink for direct writing

We report the synthesis of a bismuth ferrite (BiFeO3) (BFO) precursor-based ink via wet chemical route followed by extrusion-based direct writing on fluorine-doped tin oxide (FTO), indium-doped tin oxide (ITO), and quartz substrates. A stable aggregation-free ink is developed, based on sol–gel route that yields phase-pure BFO characterised by X-ray diffraction, scanning electron microscopy, Raman, UV–vis spectroscopy, contact angle and viscosity. Optical bandgap varies from 2.5 to 2.8 eV, as a function of particle size going from 47 to 116 nm. The viscosity of the synthesized ink is 60 mPa.s with contact angles below 90°, indicating good substrate wettability, compatibility, and suitability for printing. Printed BFO films, due to their porous nature, indicate photocatalysis and gas sensing to be promising avenues for future work.