Fig. 11

STEM imaging of a cryptomelane domain in crystal type 4 of MndBi3_10y. STEM observation of a cryptomelane domain in MndBi3_10y (a). Electron density is maximum when color is white, and minimum when color is black. b Is the same image after post-processing. Most of the particle is made of [2 × 2] tunnel structures, but [3 × 2] structures are also visible. c Shows the pixel grey values in two transects (delimited in a) along and perpendicular to tunnel walls. Arrows highlight the phase shift occurring between the two signals and thus the difference in tunnel size parallel and perpendicular to the tunnel walls. d Is a magnified view of part of b (area delimited with a dotted line in b), with a sketch of [2 × 2] and [2 × 3] tunnel structures overlaid to ease interpretation