DOI: 10.17188/1709455
title: Materials Data on Sn2Ge5(SbTe5)2 by Materials Project

description: Sn2Ge4Sb2Te9GeTe crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three GeTe sheets oriented in the (0, 0, 1) direction and three Sn2Ge4Sb2Te9 sheets oriented in the (0, 0, 1) direction. In each GeTe sheet, Ge4+ is bonded in a 6-coordinate geometry to three equivalent Te2- atoms. All Ge–Te bond lengths are 2.85 Å. Te2- is bonded in a 3-coordinate geometry to three equivalent Ge4+ atoms. In each Sn2Ge4Sb2Te9 sheet, there are two inequivalent Sn3+ sites. In the first Sn3+ site, Sn3+ is bonded to six Te2- atoms to form a mixture of edge and corner-sharing SnTe6 octahedra. The corner-sharing octahedral tilt angles are 10°. There are three shorter (2.96 Å) and three longer (3.44 Å) Sn–Te bond lengths. In the second Sn3+ site, Sn3+ is bonded to six Te2- atoms to form SnTe6 octahedra that share corners with three equivalent SnTe6 octahedra, corners with three equivalent SbTe6 octahedra, edges with three equivalent SbTe6 octahedra, and edges with nine SnTe6 octahedra. The corner-sharing octahedra tilt angles range from 7–10°. There are three shorter (2.97 Å) and three longer (3.32 Å) Sn–Te bond lengths. There are four inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to six Te2- atoms to form GeTe6 octahedra that share corners with three equivalent GeTe6 octahedra, corners with three equivalent SbTe6 octahedra, edges with three equivalent SbTe6 octahedra, and edges with nine GeTe6 octahedra. The corner-sharing octahedra tilt angles range from 6–13°. There are three shorter (2.86 Å) and three longer (3.28 Å) Ge–Te bond lengths. In the second Ge4+ site, Ge4+ is bonded to six Te2- atoms to form a mixture of distorted edge and corner-sharing GeTe6 octahedra. The corner-sharing octahedra tilt angles range from 13–14°. There are three shorter (2.86 Å) and three longer (3.38 Å) Ge–Te bond lengths. In the third Ge4+ site, Ge4+ is bonded to six Te2- atoms to form a mixture of distorted edge and corner-sharing GeTe6 octahedra. The corner-sharing octahedral tilt angles are 14°. There are three shorter (2.86 Å) and three longer (3.42 Å) Ge–Te bond lengths. In the fourth Ge4+ site, Ge4+ is bonded in a 6-coordinate geometry to six Te2- atoms. There are three shorter (2.86 Å) and three longer (3.43 Å) Ge–Te bond lengths. There are two inequivalent Sb3- sites. In the first Sb3- site, Sb3- is bonded to six Te2- atoms to form SbTe6 octahedra that share corners with three equivalent SnTe6 octahedra, corners with three equivalent SbTe6 octahedra, edges with three equivalent SnTe6 octahedra, and edges with nine SbTe6 octahedra. The corner-sharing octahedra tilt angles range from 1–7°. There are three shorter (3.03 Å) and three longer (3.17 Å) Sb–Te bond lengths. In the second Sb3- site, Sb3- is bonded to six Te2- atoms to form SbTe6 octahedra that share corners with three equivalent GeTe6 octahedra, corners with three equivalent SbTe6 octahedra, edges with three equivalent GeTe6 octahedra, and edges with nine SbTe6 octahedra. The corner-sharing octahedra tilt angles range from 1–6°. There are three shorter (3.03 Å) and three longer (3.20 Å) Sb–Te bond lengths. There are nine inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to six Sn3+ atoms to form TeSn6 octahedra that share corners with three equivalent TeSn3Sb3 octahedra and edges with nine TeSn6 octahedra. The corner-sharing octahedral tilt angles are 8°. In the second Te2- site, Te2- is bonded to three equivalent Sn3+ and three equivalent Sb3- atoms to form a mixture of edge and corner-sharing TeSn3Sb3 octahedra. The corner-sharing octahedra tilt angles range from 4–8°. In the third Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent Sn3+ atoms. In the fourth Te2- site, Te2- is bonded to six Sb3- atoms to form TeSb6 octahedra that share corners with six TeSn3Sb3 octahedra and edges with twelve TeSb6 octahedra. The corner-sharing octahedral tilt angles are 4°. In the fifth Te2- site, Te2- is bonded in a 6-coordinate geometry to three equivalent Ge4+ atoms. In the sixth Te2- site, Te2- is bonded in a 6-coordinate geometry to six Ge4+ atoms. In the seventh Te2- site, Te2- is bonded in a 6-coordinate geometry to six Ge4+ atoms. In the eighth Te2- site, Te2- is bonded to three equivalent Ge4+ and three equivalent Sb3- atoms to form a mixture of edge and corner-sharing TeGe3Sb3 octahedra. The corner-sharing octahedra tilt angles range from 4–11°. In the ninth Te2- site, Te2- is bonded to six Ge4+ atoms to form a mixture of distorted edge and corner-sharing TeGe6 octahedra. The corner-sharing octahedral tilt angles are 11°.