(a) Raw intensity data of δ-MnO2 equilibrated at pH 10 (dBi10), 6 (dBi6) and 3 (dBi3). Broad Bragg peaks are observed up to the maximal q value of 11 Å−1. Intensity at higher q is suppressed by the rapid fall off of the composition-averaged scattering factor with increasing diffraction angle. The inset shows on an expanded scale the reduction of the lattice a and b parameters at acidic pH as a result of the increase of layer vacancies. (b) The reduced structure function F(q) from the same data after making corrections for experimental effects (Wagner, 1978) and dividing the scattered intensity by and multiplying it by q to amplify the diffuse intensity at high q.