Figure 4.

Structural relationship between orthorhombic Rb₂₃Sb₉Cl₅₄ and trigonal Rb₂₃Bi₇Sb₂Cl₅₄. (a) Layer-by-layer breakdown showing one-to-one mapping of MCl₆ octahedra in each layer, with Mattfeld notation denoting the occupancy of AMX composition in each octahedral environment. (b) Unit cell of each structure viewed along the b-axis with Rb atoms removed for clarity, highlighting the offset stacking of Sb^V octahedra in Rb₂₃Bi₇Sb₂Cl₅₄ that yields a tripled lattice constant c for the rhombohedral structure relative to orthorhombic Rb₂₃Sb₉Cl₅₄. (c) Unit cells of each structure’s disphenoidal layer (II) viewed along the c-axis, showing the mapping of the a and b axes of both unit cells.