Materials Data on RbNaMg6O7 by Materials Project

Abstract

RbNaMg6O7 crystallizes in the tetragonal P4mm space group. The structure is three-dimensional. Rb1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are four shorter (2.67 Å) and one longer (3.30 Å) Rb–O bond lengths. Na1+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Na–O bond lengths are 2.18 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, edges with four equivalent MgO6 octahedra, and edges with four equivalent MgO5 square pyramids. There are one shorter (2.12 Å) and four longer (2.13 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 and edges with eight MgO5 square pyramids. The corner-sharing octahedral tilt angles are 5°. There are a spread of Mg–O bond distances ranging from 2.00–2.32 Å. In the third Mg2+ site, Mg2+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Mg–O bond distances ranging from 1.89–2.54 Å. In the fourth Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 square pyramids that share corners with four equivalent MgO5 square pyramids, edges with two equivalent MgO6 octahedra, and edges with six MgO5 square pyramids. There are one shorter (2.09 Å) and four longer (2.13 Å) Mg–O bond lengths. 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 and edges with eight ORbMg5 octahedra. In the second O2- site, O2- is bonded to five Mg2+ atoms to form distorted OMg5 square pyramids that share a cornercorner with one ORbMg5 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 Rb1+ and five Mg2+ atoms to form distorted ORbMg5 octahedra that share corners with four equivalent ORbMg5 octahedra, a cornercorner with one OMg5 square pyramid, edges with four equivalent OMg6 octahedra, and edges with four equivalent OMg5 square pyramids. The corner-sharing octahedral tilt angles are 7°. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Rb1+, two equivalent Na1+, and one Mg2+ atom. In the fifth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with four equivalent OMg6 octahedra, edges with six ORbMg5 octahedra, and edges with four OMg5 square pyramids. The corner-sharing octahedra tilt angles range from 4–5°.