Materials Data on Nb4GeS8 by Materials Project

Abstract

(NbS2)2Nb2GeS4 is Molybdenite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one Nb2GeS4 sheet oriented in the (0, 0, 1) direction and two NbS2 sheets oriented in the (0, 0, 1) direction. In the Nb2GeS4 sheet, there are two inequivalent Nb3+ sites. In the first Nb3+ site, Nb3+ is bonded to six S2- atoms to form distorted NbS6 pentagonal pyramids that share corners with six equivalent GeS6 octahedra, edges with six equivalent NbS6 pentagonal pyramids, and a faceface with one GeS6 octahedra. The corner-sharing octahedral tilt angles are 44°. There are three shorter (2.50 Å) and three longer (2.51 Å) Nb–S bond lengths. In the second Nb3+ site, Nb3+ is bonded to six S2- atoms to form distorted NbS6 pentagonal pyramids that share corners with three equivalent GeS6 octahedra, edges with three equivalent GeS6 octahedra, and edges with six equivalent NbS6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 7°. There are three shorter (2.48 Å) and three longer (2.54 Å) Nb–S bond lengths. Ge4+ is bonded to six S2- atoms to form distorted GeS6 octahedra that share corners with nine NbS6 pentagonal pyramids, edges with six equivalent GeS6 octahedra, edges with three equivalent NbS6 pentagonal pyramids, and a faceface with one NbS6 pentagonal pyramid. There are three shorter (2.75 Å) and three longer (2.82 Å) Ge–S bond lengths. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 6-coordinate geometry to three equivalent Nb3+ and three equivalent Ge4+ atoms. In the second S2- site, S2- is bonded to three equivalent Nb3+ and three equivalent Ge4+ atoms to form distorted edge-sharing SNb3Ge3 octahedra. In the third S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Nb3+ atoms. In the fourth S2- site, S2- is bonded in a 3-coordinate geometry to three equivalent Nb3+ atoms. In each NbS2 sheet, Nb3+ is bonded to six equivalent S2- atoms to form distorted edge-sharing NbS6 pentagonal pyramids. All Nb–S bond lengths are 2.50 Å. S2- is bonded in a 3-coordinate geometry to three equivalent Nb3+ atoms.