Materials Data on RbMg6BO8 by Materials Project

Abstract

RbMg6BO8 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Rb1+ is bonded to six O2- atoms to form RbO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent RbO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.31 Å) and two longer (2.42 Å) Rb–O bond lengths. There are three 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 equivalent MgO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (1.89 Å) and four longer (2.31 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Mg–O bond lengths are 2.31 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share corners with six equivalent MgO6 octahedra, edges with two equivalent RbO6 octahedra, and edges with six MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–28°. There are a spread of Mg–O bond distances ranging from 2.01–2.38 Å. B3+ is bonded in a linear geometry to six O2- atoms. There is two shorter (1.42 Å) and four longer (2.31 Å) B–O bond length. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to one Rb1+ and five Mg2+ atoms to form distorted ORbMg5 octahedra that share corners with six equivalent ORbMg5 octahedra and edges with eight ORb2Mg2B2 octahedra. The corner-sharing octahedra tilt angles range from 0–20°. In the second O2- site, O2- is bonded in a distorted single-bond geometry to four equivalent Mg2+ and one B3+ atom. In the third O2- site, O2- is bonded to two equivalent Rb1+, two equivalent Mg2+, and two equivalent B3+ atoms to form distorted ORb2Mg2B2 octahedra that share corners with six ORb2Mg2B2 octahedra and edges with eight ORbMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six ORb2Mg2B2 octahedra and edges with eight ORbMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth O2- site, O2- is bonded to two equivalent Rb1+, two equivalent Mg2+, and two equivalent B3+ atoms to form distorted ORb2Mg2B2 octahedra that share corners with six OMg6 octahedra and edges with eight ORbMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.01 Å.