Fig. 6: Polytypic features within vaterite and XRD Rietveld refinement.

Schematic illustration showing the formation of the orientation variant. a Pristine structure with uniform orientations. b Polytypic structure with variants. Variants II and III can be obtained by continuous 60° rotation of the carbonate layers from variant I along the [103]_m direction. The dark area in b indicates the disordered stacking between different variants. Rietveld refinement of the experimental powder XRD pattern collected at room temperature against the c C2 model and d proposed polytypic model that contains stacking faults and orientation domains. Experimental data points are shown in cross-symbols, the calculated powder pattern is shown in green, the background is shown in red, and the difference curve between the experimental and calculated data is shown in blue color.