Materials Data on RbMg6BO7 by Materials Project

Abstract

RbMg6BO7 crystallizes in the tetragonal P4mm space group. The structure is three-dimensional. Rb is bonded to six O atoms to form RbO6 octahedra that share corners with four equivalent RbO6 octahedra, edges with four equivalent MgO6 octahedra, and edges with four equivalent MgO5 square pyramids. The corner-sharing octahedral tilt angles are 1°. There are four shorter (2.51 Å) and two longer (2.59 Å) Rb–O bond lengths. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to five O atoms to form MgO5 square pyramids that share corners with five MgO5 square pyramids, edges with four equivalent RbO6 octahedra, and edges with four equivalent MgO6 octahedra. There are one shorter (1.98 Å) and four longer (2.51 Å) Mg–O bond lengths. In the second Mg site, Mg is bonded to five O atoms to form MgO5 square pyramids that share corners with five MgO5 square pyramids and edges with four equivalent MgO6 octahedra. There are one shorter (1.99 Å) and four longer (2.51 Å) Mg–O bond lengths. In the third Mg site, Mg is bonded in a 2-coordinate geometry to four O atoms. There are a spread of Mg–O bond distances ranging from 1.90–2.58 Å. In the fourth Mg site, Mg is bonded to six O atoms to form distorted MgO6 octahedra that share corners with four equivalent MgO6 octahedra, edges with two equivalent RbO6 octahedra, edges with four equivalent MgO6 octahedra, and edges with four MgO5 square pyramids. The corner-sharing octahedra tilt angles range from 3–26°. There are a spread of Mg–O bond distances ranging from 1.90–2.57 Å. B is bonded in a linear geometry to two O atoms. Both B–O bond lengths are 1.31 Å. There are five inequivalent O sites. In the first O site, O is bonded in a distorted single-bond geometry to one Rb, four equivalent Mg, and one B atom. In the second O site, O is bonded in a distorted single-bond geometry to one Rb, four equivalent Mg, and one B atom. In the third O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with four equivalent OMg6 octahedra and edges with four equivalent ORb2Mg4 octahedra. The corner-sharing octahedral tilt angles are 3°. In the fourth O site, O is bonded to two equivalent Rb and four Mg atoms to form ORb2Mg4 octahedra that share corners with four equivalent ORb2Mg4 octahedra and edges with six OMg6 octahedra. The corner-sharing octahedra tilt angles range from 1–2°. In the fifth O site, O is bonded in a square co-planar geometry to four Mg atoms.