DOE OSTI2020
Tl4SnSe3 crystallizes in the monoclinic P2_1 space group. The structure is two-dimensional and consists of two Tl4SnSe3 sheets oriented in the (0, 0, 1) direction. In one of the Tl4SnSe3 sheets, there are twelve inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.17–3.40 Å. In the second 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 3.07–3.71 Å. In the third Tl1+ site, Tl1+ is bonded in a 2-coordinate geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.04–3.74 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 3.10–3.74 Å. In the fifth 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 3.08–3.67 Å. In the sixth 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 3.09–3.64 Å. In the seventh 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 3.23–3.50 Å. In the eighth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.10–3.47 Å. In the ninth 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 3.07–3.35 Å. In the tenth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.07–3.45 Å. In the eleventh Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.07–3.36 Å. In the twelfth Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.07–3.30 Å. There are three inequivalent Sn2+ sites. In the first Sn2+ site, Sn2+ is bonded in a distorted T-shaped geometry to three Se2- atoms. There are a spread of Sn–Se bond distances ranging from 2.75–2.85 Å. In the second Sn2+ site, Sn2+ is bonded in a distorted T-shaped geometry to three Se2- atoms. There are one shorter (2.78 Å) and two longer (2.86 Å) Sn–Se bond lengths. In the third Sn2+ site, Sn2+ is bonded in a distorted T-shaped geometry to three Se2- atoms. There are a spread of Sn–Se bond distances ranging from 2.71–2.78 Å. There are nine inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 7-coordinate geometry to six Tl1+ and one Sn2+ atom. In the second Se2- site, Se2- is bonded in a 7-coordinate geometry to six Tl1+ and one Sn2+ atom. In the third Se2- site, Se2- is bonded in a 7-coordinate geometry to six Tl1+ and one Sn2+ atom. In the fourth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Tl1+ and one Sn2+ atom. In the fifth Se2- site, Se2- is bonded in a distorted octahedral geometry to five Tl1+ and one Sn2+ atom. In the sixth Se2- site, Se2- is bonded in a 5-coordinate geometry to four Tl1+ and one Sn2+ atom. In the seventh Se2- site, Se2- is bonded in a 8-coordinate geometry to seven Tl1+ and one Sn2+ atom. In the eighth Se2- site, Se2- is bonded in a 7-coordinate geometry to six Tl1+ and one Sn2+ atom. In the ninth Se2- site, Se2- is bonded in a 7-coordinate geometry to six Tl1+ and one Sn2+ atom. In one of the Tl4SnSe3 sheets, there are four inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.07–3.33 Å. In the second Tl1+ site, Tl1+ is bonded in a distorted rectangular see-saw-like geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.07–3.41 Å. In the third 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 3.07–3.64 Å. In the fourth Tl1+ site, Tl1+ is bonded in a 2-coordinate geometry to four Se2- atoms. There are a spread of Tl–Se bond distances ranging from 3.06–3.71 Å. Sn2+ is bonded in a distorted T-shaped geometry to three Se2- atoms. There are one shorter (2.74 Å) and two longer (2.86 Å) Sn–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 7-coordinate geometry to six Tl1+ and one Sn2+ atom. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to four Tl1+ and one Sn2+ atom. In the third Se2- site, Se2- is bonded in a 7-coordinate geometry to six Tl1+ and one Sn2+ atom.