It is evident from XRD analysis of Series 2 (Fig. ), that as Ti content decreases and Mn content increases, there is a clear gradual shift in peak position away from the m = 5 structure and towards the m = 6 Aurivillius phase. As β increases from 0 to 0.6, the 2θ position of the (008) reflection shifts from 13.6° to 14.4° and the position of the (0010) reflection shifts from 17.6° to 18.0°. While the m = 5 structure is maintained, these shifts correspond to movements towards the expected positions for the (0010) and (0012) for an m = 6 structure. A similar trend in asymmetric peak shift on aliovalent substitution is observed in Series 3 (Bi6Ti3.2-γFe1.3+γMn0.5O18 (γ = 0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6, Fig. )), where the B-site concentration of Ti is decreased, and the concentration of Fe is increased. For example, as  increases from 0 to 0.6, the 2θ position of the (008) reflection moves from 13.4° to 14.5° and the position of the (0010) reflection moves from 17.5° to 18.1°.