CLASSIFICATION OF HEAVY-METAL FLUORIDES - FLUORIDES WITH HIGH WATER CONTENTS

Five fluoride structures differing in the character of linkage of cati onic polyhedra and in relative water contents are considered. The cati onic sublattice is four-layered (ABAC) in K2Cu(ZrF6)(2) . 6H(2)O, face -centered (F-type, ABC) in CuZrF6 . 4H(2)O, primitive cubic (P-type) i n Cu-3(ZrF7)(2) . 16H(2)O, hexagonal one-layered (AA) in Cu2ZrF8 . 12H (2)O, and hexagonal two-layered (AB) in Zr2F8 . 6H(2)O. Some structure s have considerably distorted symmetries of cationic sublattices compa red to anhydrous structures because of the anisotropy of cation surrou ndings in the first, second, and third spheres, bur all characteristic close-packed cation planes of the corresponding structural types are retained. In structures with cation-cation distances of similar to 3.5 Angstrom, dimeric cations are arranged as single fragments for planes with d(hkl) > 3.5 Angstrom or as separate fragments for planes with s maller d(hkl).