“…8,15,16 However, experimental results up to date have never observed a real tetragonal phase of pure BFO, or to be precise, the phase has been confirmed as a monoclinic phase with several possible space groups of Cc, Cm, Pm, or Pc symmetry. 10,12,17 Such low-symmetry phases (here labeled as tetragonal-like phase) usually serve as a structural intermediate between rhombohedral and tetragonal phases, which is easily observed in morphotropic phase boundaries (MPBs) of perovskite ferroelectrics. [9][10][11][12][13][18][19][20] structure closest to pure tetragonal has been observed in a very thin film (∼7 nm), reported by Pailloux et al 21 Another way is using the modification such as the substitution of Bi ions by Ba ions.…”