(a) PDFs of AcidBir (data from Zhu et al., 2012) and KBi8. (b)–(d) Three equivalent fits of the AcidBir PDF. Regressed parameter values are given in the supplementary materials
, Table S2. (b) Model 1: orthogonal layer cell and initial K and H2O positions set to the values previously refined by Zhu et al. (2012). (c) Model 2: hexagonal layer cell (a = 31/2b) and initial K and H2O positions set to the values previously refined by Zhu et al. (2012). (d) Model 3: hexagonal layer cell and K and H2O initially positioned as in KBi8 (Gaillot et al., 2003). The expanded 1.0–10.0 Å region in the top inset shows that AcidBir has a lower Mn⋯Mn1IL correlation than KBi8, which is consistent with the absence of interlayer Mn in this material (Zhu et al., 2012). It also shows that the two nanomanganates have nearly the same short-range layer structure but a distinctive medium-to-long-range structure above 7.2–7.3 Å because of the turbostratism of AcidBir.