DOI: 10.17188/1653721
title: Materials Data on RbNaMg6O7 by Materials Project

description: RbNaMg6O7 crystallizes in the tetragonal P4mm space group. The structure is three-dimensional. Rb1+ is bonded to five O2- atoms to form RbO5 square pyramids that share a cornercorner with one MgO5 square pyramid, corners with four equivalent RbO5 square pyramids, edges with four equivalent NaO6 octahedra, and edges with four equivalent MgO6 octahedra. There are four shorter (2.32 Å) and one longer (2.53 Å) Rb–O bond lengths. Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent NaO6 octahedra, edges with four equivalent MgO6 octahedra, and edges with four equivalent RbO5 square pyramids. The corner-sharing octahedra tilt angles range from 0–5°. There are a spread of Na–O bond distances ranging from 2.28–2.32 Å. There are four 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 NaO6 octahedra, corners with four equivalent MgO6 octahedra, edges with four equivalent MgO6 octahedra, and edges with four equivalent MgO5 square pyramids. The corner-sharing octahedra tilt angles range from 0–5°. There are a spread of Mg–O bond distances ranging from 1.98–2.32 Å. In the second Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 square pyramids that share a cornercorner with one RbO5 square pyramid, corners with four equivalent MgO5 square pyramids, and edges with eight MgO6 octahedra. There are one shorter (1.91 Å) and four longer (2.32 Å) Mg–O bond lengths. In the third Mg2+ site, Mg2+ is bonded in a square co-planar geometry to four O2- atoms. There are a spread of Mg–O bond distances ranging from 2.03–2.32 Å. 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 two equivalent NaO6 octahedra, edges with six MgO6 octahedra, edges with two equivalent RbO5 square pyramids, and edges with two equivalent MgO5 square pyramids. The corner-sharing octahedral tilt angles are 9°. There are a spread of Mg–O bond distances ranging from 2.19–2.33 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to one Na1+ and five Mg2+ atoms to form ONaMg5 octahedra that share corners with six ONaMg5 octahedra and edges with eight ORb2Na2Mg2 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the second O2- site, O2- is bonded to one Na1+ and five Mg2+ atoms to form ONaMg5 octahedra that share corners with six ONaMg5 octahedra and edges with twelve ORbMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–9°. In the third O2- site, O2- is bonded to one Rb1+ and five Mg2+ atoms to form ORbMg5 octahedra that share corners with four equivalent ORbMg5 octahedra and edges with twelve ONaMg5 octahedra. The corner-sharing octahedral tilt angles are 9°. In the fourth O2- site, O2- is bonded to two equivalent Rb1+, two equivalent Na1+, and two Mg2+ atoms to form ORb2Na2Mg2 octahedra that share corners with six ORb2Na2Mg2 octahedra and edges with ten ONaMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–8°. In the fifth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six ORb2Na2Mg2 octahedra and edges with ten ONaMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–9°.