Crystal chemistry of germanates: Characteristic structural features of Li,Ge-germanates

Crystallochemical classification of eleven compounds from the Li-germanate family is suggested. Depending on the set of the primary building units (PB U) (M-octahedra of the composition [GeO6] and T-tetrahedra of the compositi on [GeO4]) and the type of their "condensation," these germanates are divid ed into three crystallochemical groups: framework MT-structures (four phase s), condensed MT-structures (two phases), and tetrahedral T-condensed struc tures (five phases). The structural characteristics of the framework Li,Ge- germanates are considered, i.e., their symmetry, crystallographically indep endent sets of the primary building units, framework architecture, and the types of chains and layers of the (Ge,O)-radicals. (C) 2000 MAIK "Nauka/Int erperiodica".