DOI: 10.17188/1743788
title: Materials Data on KRbMg14O15 by Materials Project

description: RbKMg14O15 crystallizes in the orthorhombic Pmm2 space group. The structure is three-dimensional. Rb1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are two shorter (2.47 Å) and two longer (2.52 Å) Rb–O bond lengths. K1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of K–O bond distances ranging from 2.34–2.65 Å. There are ten inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share corners with four MgO5 trigonal bipyramids and edges with two equivalent MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 1.95–2.14 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, edges with six MgO6 octahedra, and edges with four MgO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 3°. There are a spread of Mg–O bond distances ranging from 2.01–2.13 Å. In the third Mg2+ site, Mg2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mg–O bond distances ranging from 2.15–2.61 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share corners with four equivalent MgO6 octahedra, edges with four MgO6 octahedra, and edges with three MgO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 1–26°. There are a spread of Mg–O bond distances ranging from 2.08–2.67 Å. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, a cornercorner with one MgO5 trigonal bipyramid, and edges with four MgO6 octahedra. The corner-sharing octahedral tilt angles are 7°. There are a spread of Mg–O bond distances ranging from 1.97–2.44 Å. In the sixth Mg2+ site, Mg2+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.94 Å) and two longer (2.02 Å) Mg–O bond length. In the seventh Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share corners with three MgO6 octahedra, corners with two equivalent MgO5 trigonal bipyramids, edges with four MgO6 octahedra, and edges with four equivalent MgO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 0–21°. There are a spread of Mg–O bond distances ranging from 2.10–2.13 Å. In the eighth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with two equivalent MgO5 trigonal bipyramids, edges with two equivalent MgO6 octahedra, and edges with six MgO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 7°. There are a spread of Mg–O bond distances ranging from 1.99–2.27 Å. In the ninth Mg2+ site, Mg2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Mg–O bond distances ranging from 1.92–2.40 Å. In the tenth Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share corners with five MgO5 trigonal bipyramids, edges with five MgO6 octahedra, and edges with two equivalent MgO5 trigonal bipyramids. There are a spread of Mg–O bond distances ranging from 2.05–2.21 Å. There are eleven inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ atoms to form distorted OMg5 square pyramids that share a cornercorner with one OKMg5 octahedra, corners with two equivalent OMg5 square pyramids, corners with two equivalent OK2Mg3 trigonal bipyramids, and edges with four OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second O2- site, O2- is bonded to one K1+ and five Mg2+ atoms to form OKMg5 octahedra that share corners with two equivalent OKMg5 octahedra, a cornercorner with one OMg5 square pyramid, corners with four OMg5 trigonal bipyramids, and edges with four OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the third O2- site, O2- is bonded to five Mg2+ atoms to form OMg5 trigonal bipyramids that share corners with four OKMg5 octahedra, corners with two equivalent OMg5 trigonal bipyramids, and edges with two equivalent OMg6 octahedra. The corner-sharing octahedra tilt angles range from 12–71°. In the fourth O2- site, O2- is bonded in a 6-coordinate geometry to six Mg2+ atoms. In the fifth O2- site, O2- is bonded in a 6-coordinate geometry to six Mg2+ atoms. In the sixth O2- site, O2- is bonded to two equivalent K1+ and three Mg2+ atoms to form distorted OK2Mg3 trigonal bipyramids that share corners with five OKMg5 octahedra, corners with two equivalent OMg5 square pyramids, and corners with two equivalent OK2Mg3 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 0–66°. In the seventh O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with two equivalent OMg6 octahedra, corners with two equivalent OK2Mg3 trigonal bipyramids, and edges with two equivalent OMg5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 10°. In the eighth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with two equivalent OMg6 octahedra, a cornercorner with one OK2Mg3 trigonal bipyramid, edges with six OKMg5 octahedra, and edges with two equivalent OMg5 square pyramids. The corner-sharing octahedral tilt angles are 3°. In the ninth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Rb1+ and three Mg2+ atoms. In the tenth O2- site, O2- is bonded in a 5-coordinate geometry to one K1+ and four Mg2+ atoms. In the eleventh 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 trigonal bipyramid, edges with three OKMg5 octahedra, and an edgeedge with one OMg5 square pyramid. The corner-sharing octahedra tilt angles range from 2–45°.