Structure and multiferroic properties of Bi5FeTi3O15 thin films prepared by the sol–gel method

The Bi5FeTi3O15 (BFTO) films of layered structure have been fabricated on Pt/Ti/SiO2/Si substrates by the sol–gel method. The thermal decomposition behaviors of precursor powder were examined using thermo-gravimetric and differential scanning calorimeters analysis. The optimal heat treatment process for BFTO films were determined to be low-temperature drying at 200 °C for 4 min and high-temperature drying at 350 °C for 5 min followed by annealing at 740 °C for 60 min, which led to the formation of compact films with uniform grains of ~300 nm. The structural, surface topography, ferroelectric and magnetic properties of the films were investigated. The remnant polarization (2Pr) of BFTO thin films under an applied electric field of ~550 kV/cm are determined to be 67.5 μC/cm2. Meanwhile, the weak ferromagnetic properties of the BFTO films were observed at room temperature.