Phase transition and huge ferroelectric polarization observed in BiFe1−xGaxO3 thin films

We prepared the chemical-solution deposited films of BiFe1−xGaxO3, which was previously only possibly synthesized under high-pressure and high-temperature. The thin films crystallized in rhombohedral perovskite structure (R3c) up to x = 0.05 and in tetragonal-like monoclinic structure (Cm) above x = 0.2. The coexistence of R3c and Cm phases was observed at x = 0.1. It is found that Bi-based film with coexistence phase exhibits a huge ferroelectric polarization of 230 μC cm−2, which can be attributed to the presence of the morphotropic phase boundary.