DOI: 10.17188/1674676
title: Materials Data on CsRbMg6O7 by Materials Project

description: CsRbMg6O7 crystallizes in the tetragonal P4mm space group. The structure is two-dimensional and consists of one CsRbMg6O7 sheet oriented in the (0, 0, 1) direction. Cs1+ is bonded to five O2- atoms to form distorted CsO5 square pyramids that share a cornercorner with one MgO6 octahedra, corners with four equivalent CsO5 square pyramids, and edges with four equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.25 Å) and one longer (2.77 Å) Cs–O bond lengths. Rb1+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All Rb–O bond lengths are 2.78 Å. There are four inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 square pyramids that share corners with four equivalent MgO5 square pyramids and edges with eight MgO6 octahedra. There are one shorter (1.93 Å) and four longer (2.24 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 four equivalent MgO6 octahedra, a cornercorner with one CsO5 square pyramid, edges with four equivalent MgO6 octahedra, and edges with four equivalent MgO5 square pyramids. The corner-sharing octahedral tilt angles are 7°. There are a spread of Mg–O bond distances ranging from 2.01–2.24 Å. In the third Mg2+ site, Mg2+ is bonded in a T-shaped geometry to three O2- atoms. There are one shorter (1.99 Å) and two longer (2.22 Å) Mg–O bond lengths. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with four equivalent MgO6 octahedra, edges with six MgO6 octahedra, edges with two equivalent CsO5 square pyramids, and edges with two equivalent MgO5 square pyramids. The corner-sharing octahedra tilt angles range from 11–15°. There are a spread of Mg–O bond distances ranging from 2.14–2.43 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ atoms to form OMg5 square pyramids that share corners with four equivalent OMg5 square pyramids, corners with four equivalent OCs2Rb2Mg trigonal bipyramids, and edges with eight OCsMg5 octahedra. In the second O2- site, O2- is bonded to five Mg2+ atoms to form OMg5 square pyramids that share a cornercorner with one OCsMg5 octahedra, corners with four equivalent OMg5 square pyramids, and edges with four equivalent OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the third O2- site, O2- is bonded to one Cs1+ and five Mg2+ atoms to form distorted OCsMg5 octahedra that share corners with four equivalent OCsMg5 octahedra, a cornercorner with one OMg5 square pyramid, edges with four equivalent OMg6 octahedra, edges with four equivalent OMg5 square pyramids, and edges with four equivalent OCs2Rb2Mg trigonal bipyramids. The corner-sharing octahedral tilt angles are 15°. In the fourth O2- site, O2- is bonded to two equivalent Cs1+, two equivalent Rb1+, and one Mg2+ atom to form distorted OCs2Rb2Mg trigonal bipyramids that share a cornercorner with one OMg6 octahedra, corners with two equivalent OMg5 square pyramids, corners with four equivalent OCs2Rb2Mg trigonal bipyramids, edges with two equivalent OCsMg5 octahedra, and edges with four equivalent OCs2Rb2Mg trigonal bipyramids. The corner-sharing octahedral tilt angles are 0°. In the fifth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with four equivalent OMg6 octahedra, a cornercorner with one OCs2Rb2Mg trigonal bipyramid, edges with six OCsMg5 octahedra, and edges with four OMg5 square pyramids. The corner-sharing octahedra tilt angles range from 7–14°.