Our simulations reveal that this occurs due to significant displacements of the outer Ti cations (and also the Fe cations) towards the [Bi2O2 ] 2+ interlayers, leading to notable distortions in the TiO6 which might be expected based on the DOS associated with dx2-y2 and dz2 moving apart as indicated in the DFT results. However, the shift to higher energy of the dz2 orbital is due to increased hybridization with the O2p. This will increase the DOS in this energy window and will also increase the transition matrix element, while the opposite effect will occur for the dx2-y2 orbitals, meaning a marginal net effect on the peak intensities. ). Values for the out-of-plane displacement for the outer perovskite layer (0.426 Å) in m = 5 B6TFMO are comparable to those found for the perovskite layers next to the [Bi2O2] 2+ interfaces in other Aurivillius systems. Newnham et al. reported out-of-plane B-site cations displacements in the layers next to [Bi2O2] 2+ of 0.42 Å and 0.35 Å for the Bi3TiNbO9 (m = 2) and Bi4Ti3012 (m = 3) systems, respectively. Due to the breaking of the horizontal mirror plane within the odd-layered Aurivillius systems (with retention of a twofold rotation axis parallel to a), a minor net out-of-plane polarization component along the c-axis is allowed, in conjunction with the major ferroelectric polarization along the b-axis direction. , . This results in domains within m = 5 B6TFMO displaying either a net-up or net-down outof-plane polarization , .