Classification of heavy metal fluorides. Fluorides with high water contents

Five fluoride structures differing in the character of linkage of cationic polyhedra and in relative water contents are considered. The cationic sublattice is four-layered (ABAC) in K₂Cu(ZrF₆)₂·6H₂O, face-centered (F-type, ABC) in CuZrF₆·4H₂O primitive cubic (P-type) in Cu₃(ZrF₇)₂·16H₂O, hexagonal one-layered (AA) in Cu₂ZrF₈·12H₂O and hexagonal two-layered (AB) in Zr₂F₈·6H₂O. Some structures have considerably distorted symmetries of cationic sublattices compared to anhydrous structures because of the anisotropy of cation surroundings in the first, second, and third spheres, but al characteristic close-packed cation planes of the corresponding structural types are retained. In structures with cation-cation distances of ～3.5 Å, dimeric cations are arranged as single fragments for planes with d_hkl>3.5 Å or as separate fragments for planes with smaller d_hkl.