Effects of excessive Bi on the structure and the properties of Aurivillius Bi5.25La0.75Fe2Ti3O18 thin films

Abstract

The effects of excessive Bi on the structural, electrical and multiferroic properties of the La-doped Bi6Fe2Ti3O18 (Bi5.25La0.75Fe2Ti3O18) thin films prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method are reported. The structures of the thin films were studied by using X-ray diffraction, Raman scattering spectroscopy and scanning electron microscopy. From the experimental comparisons, a low electrical leakage current of 1.84 × 10-5 A/cm2 at 100 kV/cm and enhanced ferroelectric properties, such as a large remnant polarization (2Pr) of 10.5 μC/cm2 and a low coercive field (2Ec) of 400 kV/cm at 485 kV/cm, were observed for the 5% Biexcess La-doped Bi6Fe2Ti3O18 thin film. The formation of a stable bismuth layer-structured phase, a lower c-axis orientation, an optimum crystallinity and a dense microstructure with a smooth surface morphology correlate with the improved electrical and multiferroic properties of the 5% Bi-excessive Bi6Fe2Ti3O18 thin film.