DOI: 10.17188/1672103
title: Materials Data on RbMg14CrO16 by Materials Project

description: RbMg14CrO16 is Molybdenum Carbide MAX Phase-derived structured and crystallizes in the orthorhombic Pmmm space group. The structure is three-dimensional. Rb1+ is bonded to six O2- atoms to form RbO6 octahedra that share corners with two equivalent RbO6 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 two shorter (2.20 Å) and four longer (2.43 Å) Rb–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 RbO6 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 1.91–2.26 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CrO6 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 2.09–2.21 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent RbO6 octahedra, edges with two equivalent CrO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–11°. There are a spread of Mg–O bond distances ranging from 2.14–2.21 Å. 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 octahedra tilt angles range from 0–4°. There are four shorter (2.18 Å) and two longer (2.20 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, edges with two equivalent RbO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–10°. There are a spread of Mg–O bond distances ranging from 2.10–2.25 Å. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent CrO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Mg–O bond distances ranging from 2.16–2.20 Å. In the seventh Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent RbO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–10°. There are a spread of Mg–O bond distances ranging from 2.10–2.25 Å. In the eighth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent MgO6 octahedra, an edgeedge with one RbO6 octahedra, an edgeedge with one CrO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 3–13°. There are a spread of Mg–O bond distances ranging from 2.13–2.23 Å. Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with two equivalent RbO6 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 Cr–O bond distances ranging from 1.93–2.20 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded to one Rb1+ and five Mg2+ atoms to form ORbMg5 octahedra that share corners with six ORbMg5 octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–10°. In the second O2- site, O2- is bonded to five Mg2+ and one Cr3+ atom to form OMg5Cr octahedra that share corners with six ORbMg5 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 six Mg2+ atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra and edges with twelve ORbMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. In the fourth O2- site, O2- is bonded to two equivalent Rb1+ and four Mg2+ atoms to form ORb2Mg4 octahedra that share corners with six ORb2Mg4 octahedra and edges with twelve ORbMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth O2- site, O2- is bonded to four Mg2+ and two equivalent Cr3+ atoms to form OMg4Cr2 octahedra that share corners with six ORb2Mg4 octahedra and edges with twelve OMg5Cr octahedra. The corner-sharing octahedral tilt angles are 0°. In the sixth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six ORb2Mg4 octahedra and edges with twelve ORbMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the seventh O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg4Cr2 octahedra and edges with twelve OMg5Cr octahedra. The corner-sharing octahedral tilt angles are 0°. In the eighth O2- site, O2- is bonded to one Rb1+, four Mg2+, and one Cr3+ atom to form ORbMg4Cr octahedra that share corners with six ORbMg4Cr octahedra and edges with twelve ORbMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–11°. In the ninth O2- site, O2- is bonded to one Rb1+, four Mg2+, and one Cr3+ atom to form ORbMg4Cr octahedra that share corners with six ORbMg4Cr octahedra and edges with twelve ORbMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–11°. There are two shorter (2.21 Å) and two longer (2.23 Å) O–Mg bond lengths. In the tenth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six ORbMg4Cr octahedra and edges with twelve ORbMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–9°.