As determined previously , , , the [Bi2O2] 2+ -perovskite interface within the B6TFMO unit cell drives a change in the internal elastic strain energies and electrostatic energies across the perovskite layers within B6TFMO. Kikuchi's model of the Aurivillius phases considers the compressive forces felt at the outer perovskite layers (pseudocubic a = 3.89 Å) imposed by the [Bi2O2] 2+ interface (a = 3.80 Å) and shows how the change in elastic strain energy within Aurivillius phases is critical to the stability of a particular phase. The approach developed by Moore et al. , found that the elastic strain imposed onto the perovskite layers results in the average c/a ratio changing from ~1.25 for the outer layers to ~1.15 at the center layers of the perovskite cells. When considering the impact of elastic strain to the environment within which the Ti cations reside, it follows that the bond lengths between the transition metal and the O ligands will be altered. This ensues that the more highly strained BO6 octahedra next to the [Bi2O2] 2+ interface will be more tetragonally distorted compared to those further from the interface.