Composition variations of lattice parameters of TlIn(Se1 – x)2, TlIn(Se1 – xSx)2, and TlIn1 – xGaxSe2 mixed crystals

✍ Scribed by N. M. Gasanly; H. Özkan; A. Çulfaz

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 260 KB
• Volume: 30
• Category: Article
• ISSN: 0232-1300
• DOI: 10.1002/crat.2170300117

✦ Synopsis

Abstract

TlInSe~2~ and TlInTe~2~ crystallize in a tetragonal cell (space group 14/mcm) (MÜLLER et al.). A primitive cell of these ternary crystals contains two formula units. All the Tl atoms in these compounds are univalent. The In atoms are trivalent being in a tetrahedral environment consisting of Se or Te atoms. InSe~4~ or InTe~4~ fragments of a unit cell form the chains extended along c‐axis coinciding with [001] directions. Such chains are bonded to each other by Tl atoms.

TlGaSe~2~ and TlInS~2~ crystals belong to the monoclinic system (space group C2/c) (MÜLLER, HAHN; WONG‐NG et al.). The primitive cell of these crystals contains eight formula units. The lattice of TlGaSe~2~ crystals consists of strictly periodic two‐dimensional layers arranged parallel to the (001) plane. Each successive layer is turned through a right angle with respect to the previous one. The fundamental structural unit of a layer is the Ga~4~Se~10~ polyhedron representing a combination of four elementary GaSe~4~ tetrahedra linked together by bridging Se atoms. The Tl atoms are in trigonal prismatic voids resulting from the combination of the Ga~4~Se~10~ polyhedra into a layer. The Tl atoms form nearly planar chains along the [110] and [110] directions.