Materials Data on Ge(SbTe2)2 by Materials Project

Abstract

Ge(SbTe2)2 is MAX Phase-like structured and crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three Ge(SbTe2)2 sheets oriented in the (0, 0, 1) direction. Ge4+ is bonded to six Te2- atoms to form GeTe6 octahedra that share corners with three equivalent SbTe6 octahedra, edges with three equivalent SbTe6 octahedra, and edges with six equivalent GeTe6 octahedra. The corner-sharing octahedral tilt angles are 6°. There are three shorter (2.85 Å) and three longer (3.27 Å) Ge–Te bond lengths. There are two inequivalent Sb2+ sites. In the first Sb2+ site, Sb2+ is bonded to six Te2- atoms to form a mixture of edge and corner-sharing SbTe6 octahedra. The corner-sharing octahedral tilt angles are 1°. There are three shorter (3.01 Å) and three longer (3.20 Å) Sb–Te bond lengths. In the second Sb2+ site, Sb2+ 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 (3.17 Å) Sb–Te bond lengths. There are four inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent Sb2+ atoms. In the second Te2- site, Te2- is bonded to six Sb2+ atoms to form TeSb6 octahedra that share corners with three equivalent TeGe3Sb3 octahedra and edges with nine TeSb6 octahedra. The corner-sharing octahedral tilt angles are 4°. In the third Te2- site, Te2- is bonded to three equivalent Ge4+ and three equivalent Sb2+ atoms to form a mixture of edge and corner-sharing TeGe3Sb3 octahedra. The corner-sharing octahedral tilt angles are 4°. In the fourth Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent Ge4+ atoms.