DOE OSTI2020
Sn5GeTe6(SnGeTe2)3 crystallizes in the monoclinic Pm space group. The structure is two-dimensional and consists of one Sn5GeTe6 sheet oriented in the (1, 0, 0) direction and one SnGeTe2 sheet oriented in the (1, 0, 0) direction. In the Sn5GeTe6 sheet, there are five inequivalent Sn2+ sites. In the first Sn2+ site, Sn2+ is bonded in a 3-coordinate geometry to three Te2- atoms. All Sn–Te bond lengths are 2.99 Å. In the second Sn2+ site, Sn2+ is bonded in a 5-coordinate geometry to five Te2- atoms. There are three shorter (3.00 Å) and two longer (3.57 Å) Sn–Te bond lengths. In the third Sn2+ site, Sn2+ is bonded in a 5-coordinate geometry to five Te2- atoms. There are a spread of Sn–Te bond distances ranging from 3.00–3.52 Å. In the fourth Sn2+ site, Sn2+ is bonded in a 5-coordinate geometry to three Te2- atoms. There are two shorter (3.00 Å) and one longer (3.05 Å) Sn–Te bond lengths. In the fifth Sn2+ site, Sn2+ is bonded in a 5-coordinate geometry to three Te2- atoms. There are two shorter (3.01 Å) and one longer (3.03 Å) Sn–Te bond lengths. Ge2+ is bonded to five Te2- atoms to form distorted edge-sharing GeTe5 square pyramids. There are a spread of Ge–Te bond distances ranging from 2.78–3.55 Å. There are six inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 5-coordinate geometry to three Sn2+ atoms. In the second Te2- site, Te2- is bonded in a 5-coordinate geometry to three Sn2+ atoms. In the third Te2- site, Te2- is bonded in a 5-coordinate geometry to four Sn2+ and one Ge2+ atom. In the fourth Te2- site, Te2- is bonded in a 3-coordinate geometry to one Sn2+ and two equivalent Ge2+ atoms. In the fifth Te2- site, Te2- is bonded in a 3-coordinate geometry to five Sn2+ atoms. In the sixth Te2- site, Te2- is bonded in a 3-coordinate geometry to three Sn2+ and two equivalent Ge2+ atoms. In the SnGeTe2 sheet, there are three inequivalent Sn2+ sites. In the first Sn2+ site, Sn2+ is bonded in a 5-coordinate geometry to three Te2- atoms. There are two shorter (3.00 Å) and one longer (3.03 Å) Sn–Te bond lengths. In the second Sn2+ site, Sn2+ is bonded in a 3-coordinate geometry to three Te2- atoms. There are two shorter (3.00 Å) and one longer (3.03 Å) Sn–Te bond lengths. In the third Sn2+ site, Sn2+ is bonded in a 6-coordinate geometry to three Te2- atoms. There are two shorter (3.00 Å) and one longer (3.05 Å) Sn–Te bond lengths. There are three inequivalent Ge2+ sites. In the first Ge2+ site, Ge2+ is bonded in a 3-coordinate geometry to three Te2- atoms. There are one shorter (2.78 Å) and two longer (2.84 Å) Ge–Te bond lengths. In the second Ge2+ site, Ge2+ is bonded in a 3-coordinate geometry to three Te2- atoms. There are one shorter (2.78 Å) and two longer (2.84 Å) Ge–Te bond lengths. In the third Ge2+ site, Ge2+ is bonded in a 3-coordinate geometry to three Te2- atoms. There are one shorter (2.78 Å) and two longer (2.84 Å) Ge–Te bond lengths. There are six inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 3-coordinate geometry to two equivalent Sn2+ and one Ge2+ atom. In the second Te2- site, Te2- is bonded in a 3-coordinate geometry to two equivalent Sn2+ and one Ge2+ atom. In the third Te2- site, Te2- is bonded in a 3-coordinate geometry to two equivalent Sn2+ and one Ge2+ atom. In the fourth Te2- site, Te2- is bonded in a distorted trigonal non-coplanar geometry to one Sn2+ and two equivalent Ge2+ atoms. In the fifth Te2- site, Te2- is bonded in a distorted trigonal non-coplanar geometry to one Sn2+ and two equivalent Ge2+ atoms. In the sixth Te2- site, Te2- is bonded in a 3-coordinate geometry to one Sn2+ and two equivalent Ge2+ atoms.