High pressure synthesis and structure of a novel clathrate-type compound: Te7+xSi20−x (x ~ 2.5)

Nicolas Jaussaud (1) , Michel Pouchard (1) , Graziella Goglio (1) , Christian Cros (1) , Abdelaziz Ammar (1) , François Weill (1) , Pierre Gravereau (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

A novel clathrate-type compound, Te7+xSi20+x (x ~ 2.5), has been synthesized from the elements under high pressure and high temperature conditions. Its structure has been solved by Rietveld analysis of the XRD powder patterns combined with the results of an electron diffraction study. This structure is closely related to that of a type I clathrate, but with a different unit-cell parameter (a ~ 2 ×a0) and space group (Fd-3c instead of Pm-3n). Its main feature is that it corresponds to a double clathration of a Te atom enclosed in a partially Te substituted (12.5%) Si20 pentagonal dodecahedra, which is itself enclosed in a large Te24 polyhedron, in form of a truncated octahedron...

Mots clés: High pressure synthesis; Te–Si system; Clathrates; Solid state structure; Electron diffraction

Domaines: Matériaux

Nicolas Jaussaud, Michel Pouchard, Graziella Goglio, Christian Cros, Abdelaziz Ammar, et al.. High pressure synthesis and structure of a novel clathrate-type compound: Te7+xSi20−x (x ~ 2.5). Solid State Sciences, 2003, 5 (9), pp.1193-1200. ⟨10.1016/S1293-2558(03)00172-9⟩. ⟨hal-00177544⟩