Fig. 3: Similarity and nuance difference for the stacking of carbonates along some directions.

Structural projection of the ordered C2 vaterite along the (a) [110]_m, (b) [1\(\bar{1}\)0]_m, and (c) [010]_m directions. The black frames indicate the projection of a unit cell along the corresponding directions. The cyan vertical lines indicate the stacking feature of the Ca-C-O chains along the [001]_m direction. Arrows indicate the projected axes. The pink, blue and chartreuse balls indicate the Ca, C and O atoms respectively. Atomic resolution HAADF image simulations along the (d) [110]_m, (e) [1\(\bar{1}\)0]_m, and (f) [010]_m directions. The cyan ovals in d–f indicate the diffused streaks along the vertical direction. Scale bar in d–f is 0.5 nm.