TEM analysis (Fig. ) confirmed the increased structural rearrangement to m = 6 layered units as the Ti content within the films decreases. The thickness of a unit cell along the growth (c) axis of the Aurivillius structure can be estimated using the formula: c/2 = f + h, where h = m*p.f refers to the thickness of the [Bi2O2] 2+ interlayer, which is estimated to be 4.08 Å. The average thickness of the perovskite blocks (p) is ≈ 4.11 Å and m refers to the number of perovskite blocks per halfunit cell of the Aurivillius phase structure. Thus, c is calculated to be 41.04 Å for an m = 4 structure, c is 49.26 Å for an m = 5 structure and c is 57.48 Å for an m = 6 structure. This correlates well with the c-axis lattice parameters in the literature physically determined by x-ray and powder neutron diffraction data. TEM imaging supports the XRD findings that the Bi6Ti2.8Fe1.52Mn0.68O18 composition is primarily structured as the m = 5 phase, with a measured c-axis length of 4.6 ± 0.1 nm, which is within 10% instrumental error of the expected 4.9 nm (Fig.