Materials Data on Nb4B3C2 by Materials Project
Nb4B3C2 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are four inequivalent Nb+2.75+ sites. In the first Nb+2.75+ site, Nb+2.75+ is bonded to twelve B1- atoms to form NbB12 cuboctahedra that share corners with two equivalent NbBC5 square pyramids, edges with eight equivalent NbB12 cuboctahedra, and faces with six equivalent NbB12 cuboctahedra. There are a spread of Nb–B bond distances ranging from 2.43–2.49 Å. In the second Nb+2.75+ site, Nb+2.75+ is bonded in a 1-coordinate geometry to six B1- and one C4- atom. There are two shorter (2.36 Å) and four longer (2.39 Å) Nb–B bond lengths. The Nb–C bond length is 2.13 Å. In the third Nb+2.75+ site, Nb+2.75+ is bonded to six C4- atoms to form NbC6 octahedra that share corners with four equivalent NbC6 octahedra, a cornercorner with one NbBC5 square pyramid, edges with eight equivalent NbC6 octahedra, and edges with four equivalent NbBC5 square pyramids. The corner-sharing octahedral tilt angles are 1°. There are a spread of Nb–C bond distances ranging from 2.19–2.29 Å. In the fourth Nb+2.75+ site, Nb+2.75+ is bonded to one B1- and five C4- atoms to form NbBC5 square pyramids that share corners with two equivalent NbB12 cuboctahedra, a cornercorner with one NbC6 octahedra, corners with four equivalent NbBC5 square pyramids, edges with four equivalent NbC6 octahedra, and edges with four equivalent NbBC5 square pyramids. The corner-sharing octahedral tilt angles are 0°. The Nb–B bond length is 2.91 Å. There are one shorter (2.20 Å) and four longer (2.27 Å) Nb–C bond lengths. There are three inequivalent B1- sites. In the first B1- site, B1- is bonded in a 9-coordinate geometry to seven Nb+2.75+ and two equivalent B1- atoms. Both B–B bond lengths are 1.84 Å. In the second B1- site, B1- is bonded in a 9-coordinate geometry to six Nb+2.75+ and three B1- atoms. The B–B bond length is 1.84 Å. In the third B1- site, B1- is bonded in a 9-coordinate geometry to six equivalent Nb+2.75+ and three B1- atoms. Both B–B bond lengths are 1.81 Å. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded to six Nb+2.75+ atoms to form a mixture of corner and edge-sharing CNb6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the second C4- site, C4- is bonded to six Nb+2.75+ atoms to form a mixture of corner and edge-sharing CNb6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°.