Bi concentration dependence of structural, ferroelectric and magnetic properties of BiFeO₃ films

Bi-rich BiFeO3 films were fabricated by chemical solution deposition followed by a post-deposition annealing at 823 K in air. Not only the polycrystalline BiFeO3 phase but also the bismuth oxide phase's were formed at high excess Bi contents. This suggested that the Bi atoms were not significantly evaporated. The remanent polarization decreased as the excess Bi contents increased at 90 K, though the remanent polarization of 33 μC/cm² was still obtained at the excess Bi contents of 30 at.%. The magnetization monotonically decreased as the excess Bi content increased. It could be considered that the optimal Bi content is the stoichiometric value of BiFeO ₃ in the preparing way of the CSD followed by the annealing at 823 K.