Preparation and crystal structure of chromium silicon selenide containing a B-12 icosahedron with a tunnel structure

Chromium silicon boron selenide has been prepared by the reaction of chromi um diboride and selenium in an evacuated silica tube at a high temperature. The compound is obtained as single crystals in a low yield. The X-ray stud ies have shown that the structure consists of the three-dimensional framewo rk with a large tunnel;md the filling component in the tunnels. The former is made of Si coordinated by four silicon atoms, chromium atoms coordinated by six selenium atoms, and B-12 icosahedra. The filling component has a st rongly disordered structure and estimated to be a chain of B2Se3. Analysis of the occupational factors of the filling component has indicated that the composition of the compound is CrSi3(B-12)Se-12.(B2Se3)(1.33). (C) 2000 Pu blished by Elsevier Science S.A. All rights reserved.