Materials Data on Tl4SiSe4 by Materials Project

Abstract

Tl4SiSe4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are five inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are two shorter (3.05 Å) and two longer (3.34 Å) Tl–Se bond lengths. In the second Tl1+ site, Tl1+ is bonded in a 6-coordinate geometry to six Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.30–3.70 Å. In the third Tl1+ site, Tl1+ is bonded to five Se2- atoms to form distorted TlSe5 square pyramids that share corners with two equivalent TlSe5 square pyramids, corners with three equivalent SiSe4 tetrahedra, and an edgeedge with one SiSe4 tetrahedra. There are a spread of Tl–Se bond distances ranging from 3.21–3.54 Å. In the fourth Tl1+ site, Tl1+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.07–3.43 Å. In the fifth Tl1+ site, Tl1+ is bonded in a 4-coordinate geometry to six Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.14–3.88 Å. Si4+ is bonded to four Se2- atoms to form SiSe4 tetrahedra that share corners with three equivalent TlSe5 square pyramids and an edgeedge with one TlSe5 square pyramid. There are a spread of Si–Se bond distances ranging from 2.30–2.32 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 1-coordinate geometry to four Tl1+ and one Si4+ atom. In the second Se2- site, Se2- is bonded in a 1-coordinate geometry to six Tl1+ and one Si4+ atom. In the third Se2- site, Se2- is bonded to five Tl1+ and one Si4+ atom to form a mixture of distorted edge and corner-sharing SeTl5Si octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth Se2- site, Se2- is bonded in a 6-coordinate geometry to five Tl1+ and one Si4+ atom.