title: Ca3ZnGeO2[Ge4O12]: a Ca-Zn germanate related to the mineral taikanite.
abstract: The title compound, Ca3ZnGeO2[Ge4O12] (tricalcium zinc germanium dioxide dodecaoxidotetragermanate), adopts a taikanite-type structure. The tetrahedral [Ge4O12] chain geometry is very similar to that of the silicate chain of taikanite, i.e. BaSr2Mn(3+)2O2[Si4O12], while the major difference is found parallel to the c axis. In taikanite, Mn(3+) octahedra form an infinite zigzag chain, whereas the title compound has a chain of distorted ZnO6 octahedra, which alternates with distorted GeO4 tetrahedra connected to each other via two common edges. Eightfold-coordinated Ca(2+) polyhedra and ZnO6 octahedra form a slab parallel to (001) which alternates with another slab containing the tetrahedrally coordinated Ge sites along the c axis.
authors.affiliation: Department of Materials Science & Physics, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria.
authors.forename: Günther J
authors.initials: GJ
authors.lastname: Redhammer
keywords: CMS-XI; crystal structure; silicate mineral; single `vierer' chain germanate; taikanite-type compound