CLASSIFICATION OF HEAVY-METAL FLUORIDES - FLUORIDES WITH SQUARE-RHOMBIC CATION NET OF THE 3(2)434 TYPE

We have analyzed the cation arrangement in some structures of complex fluorides with U4+, Th4+, and Zr4+ differing in composition, symmetry, and unit cell dimensions. Using the CAS-PAN technique in the structur es Of U2F9, CsU2F9, BaZr2F10 . H2O, LiTlZr5F22, TlZrF5, NH4UF5, BaZrF6 , and TlBF4, we have isolated a distinctive structural fragment - plan ar close-packed cation nets of the 32434 type. We have described the t otality of close-filled cation planes underlying the highly symmetric structure type U2F9 selected as a standard for all structures with sim ilar cation nets. The cation-anion moiety (a polyhedral layer of high- valent cations) responsible for basic structural features is analyzed.