DOI: 10.17188/1720394
title: Materials Data on Mg30NbCO32 by Materials Project

description: Mg30NbCO32 is Molybdenum Carbide MAX Phase-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are eight inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent NbO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.09 Å) and four longer (2.14 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 1.99–2.19 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.13 Å) and two longer (2.15 Å) Mg–O bond lengths. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.12 Å) and two longer (2.18 Å) Mg–O bond lengths. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one NbO6 octahedra, an edgeedge with one CO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 2–14°. There are a spread of Mg–O bond distances ranging from 2.09–2.25 Å. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Mg–O bond distances ranging from 2.13–2.18 Å. In the seventh Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one NbO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedral tilt angles are 1°. There are a spread of Mg–O bond distances ranging from 2.11–2.17 Å. In the eighth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–9°. There are a spread of Mg–O bond distances ranging from 2.12–2.17 Å. Nb2+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent CO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (1.98 Å) and four longer (2.17 Å) Nb–O bond lengths. C2+ is bonded to six O2- atoms to form distorted CO6 octahedra that share corners with two equivalent NbO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.27 Å) and two longer (2.35 Å) C–O bond lengths. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ and one Nb2+ atom to form OMg5Nb octahedra that share corners with four OMg5Nb octahedra, corners with two equivalent OMg5C square pyramids, edges with ten OMg5Nb octahedra, and edges with two equivalent OMg4NbC square pyramids. The corner-sharing octahedral tilt angles are 0°. In the second O2- site, O2- is bonded to five Mg2+ and one C2+ atom to form distorted OMg5C square pyramids that share corners with four OMg5Nb octahedra, corners with two equivalent OMg5C square pyramids, edges with eight OMg6 octahedra, and edges with four OMg5C square pyramids. The corner-sharing octahedra tilt angles range from 4–5°. In the third O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with four OMg6 octahedra, corners with two equivalent OMg5C square pyramids, edges with ten OMg6 octahedra, and edges with two OMg5C square pyramids. The corner-sharing octahedra tilt angles range from 0–1°. In the fifth O2- site, O2- is bonded to five Mg2+ and one C2+ atom to form distorted OMg5C square pyramids that share corners with four OMg5Nb octahedra, corners with two equivalent OMg5C square pyramids, edges with eight OMg6 octahedra, and edges with four OMg5C square pyramids. The corner-sharing octahedra tilt angles range from 4–5°. There are two shorter (2.09 Å) and two longer (2.12 Å) O–Mg bond lengths. In the sixth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with four OMg6 octahedra, corners with two equivalent OMg5C square pyramids, edges with ten OMg6 octahedra, and edges with two OMg5C square pyramids. The corner-sharing octahedra tilt angles range from 0–1°. All O–Mg bond lengths are 2.15 Å. In the seventh O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra, edges with nine OMg5Nb octahedra, and edges with three OMg5C square pyramids. The corner-sharing octahedra tilt angles range from 1–5°. In the eighth O2- site, O2- is bonded to four equivalent Mg2+, one Nb2+, and one C2+ atom to form distorted OMg4NbC square pyramids that share corners with four equivalent OMg6 octahedra, corners with two equivalent OMg4NbC square pyramids, edges with eight OMg5Nb octahedra, and edges with four OMg5C square pyramids. The corner-sharing octahedral tilt angles are 10°. In the ninth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with four OMg6 octahedra, corners with two equivalent OMg4NbC square pyramids, edges with ten OMg5Nb octahedra, and edges with two OMg5C square pyramids. The corner-sharing octahedra tilt angles range from 0–2°. In the tenth O2- site, O2- is bonded to six Mg2+ atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°.