Materials Data on Nb4C3 by Materials Project
Nb4C3 is MAX Phase-derived structured and crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three Nb4C3 sheets oriented in the (0, 0, 1) direction. there are four inequivalent Nb3+ sites. In the first Nb3+ site, Nb3+ is bonded to six C4- atoms to form a mixture of distorted edge and corner-sharing NbC6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.27 Å) and three longer (2.28 Å) Nb–C bond lengths. In the second Nb3+ site, Nb3+ is bonded in a distorted T-shaped geometry to three equivalent C4- atoms. All Nb–C bond lengths are 2.16 Å. In the third Nb3+ site, Nb3+ is bonded in a distorted T-shaped geometry to three equivalent C4- atoms. All Nb–C bond lengths are 2.18 Å. In the fourth Nb3+ site, Nb3+ is bonded to six C4- atoms to form a mixture of edge and corner-sharing NbC6 octahedra. There are three shorter (2.24 Å) and three longer (2.26 Å) Nb–C bond lengths. There are three inequivalent C4- sites. In the first C4- site, C4- is bonded to six Nb3+ atoms to form a mixture of edge and corner-sharing CNb6 octahedra. The corner-sharing octahedral tilt angles are 1°. In the second C4- site, C4- is bonded to six Nb3+ atoms to form a mixture of edge, corner, and face-sharing CNb6 octahedra. The corner-sharing octahedral tilt angles are 47°. In the third C4- site, C4- is bonded to six Nb3+ atoms to form a mixture of edge, corner, and face-sharing CNb6 octahedra. The corner-sharing octahedra tilt angles range from 1–47°.