Classification of heavy metal fluorides. Fluorides with high water contents

Abstract

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 A, dimeric cations are arranged as single fragments for planes with dhkl>3.5 A or as separate fragments for planes with smaller dhkl.