DOI: 10.17188/1690497
title: Materials Data on BaMg30CrO32 by Materials Project

description: BaMg30CrO32 is Molybdenum Carbide MAX Phase-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Ba2+ is bonded to six O2- atoms to form BaO6 octahedra that share corners with six MgO6 octahedra and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.41 Å) and two longer (2.43 Å) Ba–O bond lengths. 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 BaO6 octahedra, corners with two equivalent MgO6 octahedra, corners with two equivalent CrO6 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 1.91–2.23 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent BaO6 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 (1.93 Å) and four longer (2.21 Å) Mg–O bond lengths. 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 a spread of Mg–O bond distances ranging from 2.12–2.15 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CrO6 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 (2.04 Å) and four longer (2.17 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 BaO6 octahedra, an edgeedge with one CrO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–10°. There are a spread of Mg–O bond distances ranging from 2.10–2.23 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 1–2°. There are a spread of Mg–O bond distances ranging from 2.16–2.19 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 BaO6 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 2.10–2.26 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 CrO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–6°. There are a spread of Mg–O bond distances ranging from 2.15–2.21 Å. Cr2+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six MgO6 octahedra and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.12 Å) and two longer (2.33 Å) Cr–O bond lengths. There are thirteen inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ba2+ and five Mg2+ atoms to form OBaMg5 octahedra that share corners with six OBaMg5 octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. In the second O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OBaMg5 octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. In the third O2- site, O2- is bonded to five Mg2+ and one Cr2+ atom to form a mixture of edge and corner-sharing OMg5Cr octahedra. The corner-sharing octahedra tilt angles range from 0–4°. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OBaMg5 octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are two shorter (2.10 Å) and two longer (2.17 Å) O–Mg bond lengths. In the fifth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra and edges with twelve OBaMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–5°. In the sixth O2- site, O2- is bonded to one Ba2+ and five Mg2+ atoms to form a mixture of edge and corner-sharing OBaMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. In the seventh O2- site, O2- is bonded to five Mg2+ and one Cr2+ atom to form OMg5Cr octahedra that share corners with six OBaMg5 octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. The O–Mg bond length is 2.20 Å. In the eighth O2- site, O2- is bonded to five Mg2+ and one Cr2+ atom to form OMg5Cr octahedra that share corners with six OBaMg5 octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are a spread of O–Mg bond distances ranging from 2.10–2.21 Å. In the ninth 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 0–4°. In the tenth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg5Cr octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the eleventh O2- site, O2- is bonded to five Mg2+ and one Cr2+ atom to form OMg5Cr octahedra that share corners with six OBaMg5 octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. Both O–Mg bond lengths are 2.21 Å. In the twelfth O2- site, O2- is bonded to one Ba2+ and five Mg2+ atoms to form a mixture of edge and corner-sharing OBaMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are a spread of O–Mg bond distances ranging from 1.91–2.26 Å. In the thirteenth O2- site, O2- is bonded to five Mg2+ and one Cr2+ atom to form OMg5Cr octahedra that share corners with six OMg5Cr octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are two shorter (2.10 Å) and two longer (2.21 Å) O–Mg bond lengths.