Substitution of indium for chromium in TlIn5- x Cr x Se8: crystal structure of TlIn4.811(5)Cr0.189(5)Se8

Robin Lefèvre; David Berthebaud; Franck Gascoin

doi:10.1107/S2056989017003292

Substitution of indium for chromium in TlIn_{5- x} Cr _x Se₈: crystal structure of TlIn_4.811(5)Cr_0.189(5)Se₈

Acta Crystallogr E Crystallogr Commun. 2017 Mar 14;73(Pt 4):500-502. doi: 10.1107/S2056989017003292. eCollection 2017 Apr 1.

Authors

Robin Lefèvre¹, David Berthebaud¹, Franck Gascoin¹

Affiliation

¹ Laboratoire CRISMAT UMR6508, 6 Blvd du Maréchal Juin, 14050 Caen Cedex 4, France.

Abstract

The new thallium penta-(indium/chromium) octa-selenide, TlIn_4.811(5)Cr_0.189(5)Se₈, has been synthesized by solid-state reaction. It crystallizes isotypically with TlIn₅Se₈ in the space group C2/m. Although the two Tl positions are disordered and only partially occupied, no Tl deficiency was observed. The insertion of chromium in the structure has been confirmed by EDS analysis. Chromium substitutes indium exclusively at one of three In sites, viz. at one of the positions with site symmetry 2/m (Wyckoff position 2a). In the crystal structure, edge-sharing InSe₆ octa-hedra, and (In,Cr)Se₆ octa-hedra and InSe₄ tetra-hedra make up two types of columns that are linked into a framework in which two different types of channels parallel to [010] are present. The Tl atoms are located in the larger of the channels, whereas the other, smaller channel remains unoccupied.

Keywords: crystal structure; intermetallics; pseudo-hollandite; selenide; solid solution.