DOI: 10.17188/1739200
title: Materials Data on CsHfMg14O15 by Materials Project

description: CsMg14HfO15 crystallizes in the orthorhombic Pmm2 space group. The structure is three-dimensional. Cs is bonded in a 5-coordinate geometry to five O atoms. There are a spread of Cs–O bond distances ranging from 2.81–3.02 Å. There are ten inequivalent Mg sites. In the first Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with two equivalent MgO5 square pyramids, edges with eight MgO6 octahedra, and edges with two equivalent MgO5 square pyramids. The corner-sharing octahedral tilt angles are 5°. There are a spread of Mg–O bond distances ranging from 2.01–2.23 Å. In the second Mg site, Mg is bonded to five O atoms to form MgO5 square pyramids that share corners with two equivalent MgO6 octahedra, corners with two equivalent MgO5 square pyramids, and edges with eight MgO6 octahedra. The corner-sharing octahedral tilt angles are 8°. There are one shorter (2.06 Å) and four longer (2.07 Å) Mg–O bond lengths. In the third Mg site, Mg is bonded to five O atoms to form MgO5 square pyramids that share a cornercorner with one MgO6 octahedra, corners with four equivalent MgO5 square pyramids, and edges with four MgO6 octahedra. The corner-sharing octahedral tilt angles are 3°. There are a spread of Mg–O bond distances ranging from 1.95–2.26 Å. In the fourth Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four equivalent MgO6 octahedra, a cornercorner with one MgO5 square pyramid, edges with six MgO6 octahedra, and edges with three MgO5 square pyramids. The corner-sharing octahedra tilt angles range from 2–8°. There are a spread of Mg–O bond distances ranging from 2.04–2.28 Å. In the fifth Mg site, Mg is bonded to five O atoms to form MgO5 square pyramids that share a cornercorner with one MgO6 octahedra, corners with two equivalent MgO5 square pyramids, and edges with four MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 2.04–2.14 Å. In the sixth Mg site, Mg is bonded in a bent 150 degrees geometry to two equivalent O atoms. Both Mg–O bond lengths are 2.16 Å. In the seventh Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four MgO6 octahedra, a cornercorner with one MgO5 square pyramid, edges with eight MgO6 octahedra, and edges with two equivalent MgO5 square pyramids. The corner-sharing octahedra tilt angles range from 1–14°. There are a spread of Mg–O bond distances ranging from 2.08–2.35 Å. In the eighth Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four MgO6 octahedra, edges with six MgO6 octahedra, and edges with four MgO5 square pyramids. The corner-sharing octahedra tilt angles range from 1–3°. There are a spread of Mg–O bond distances ranging from 2.07–2.34 Å. In the ninth Mg site, Mg is bonded in a rectangular see-saw-like geometry to four O atoms. There are a spread of Mg–O bond distances ranging from 2.06–2.09 Å. In the tenth Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four equivalent MgO6 octahedra, edges with seven MgO6 octahedra, and edges with three MgO5 square pyramids. The corner-sharing octahedra tilt angles range from 2–12°. There are a spread of Mg–O bond distances ranging from 2.07–2.34 Å. Hf is bonded in a 4-coordinate geometry to four O atoms. There are two shorter (1.99 Å) and two longer (2.14 Å) Hf–O bond lengths. There are eleven inequivalent O sites. In the first O site, O is bonded to one Cs and five Mg atoms to form distorted OCsMg5 octahedra that share corners with two equivalent OCsMg5 octahedra, a cornercorner with one OMg5 square pyramid, corners with two equivalent OCs2Mg3 trigonal bipyramids, edges with four OMg6 octahedra, and edges with four equivalent OMg5 square pyramids. The corner-sharing octahedral tilt angles are 6°. In the second O site, O is bonded to five Mg atoms to form OMg5 square pyramids that share a cornercorner with one OCsMg5 octahedra, corners with four OMg5 square pyramids, corners with two equivalent OCs2Mg3 trigonal bipyramids, and edges with eight OMg6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the third O site, O is bonded to five Mg atoms to form OMg5 square pyramids that share corners with four OMg5 square pyramids, corners with two equivalent OHf2Mg3 trigonal bipyramids, edges with six OMg6 octahedra, and edges with two equivalent OMg5 square pyramids. In the fourth O site, O is bonded to five Mg atoms to form OMg5 square pyramids that share a cornercorner with one OMg6 octahedra, corners with five OMg5 square pyramids, and edges with five OCsMg5 octahedra. The corner-sharing octahedral tilt angles are 2°. In the fifth O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with four equivalent OMg6 octahedra, a cornercorner with one OMg5 square pyramid, edges with three OMg6 octahedra, edges with five OMg5 square pyramids, and edges with two OCs2Mg3 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 1–2°. In the sixth O site, O is bonded to two equivalent Cs and three Mg atoms to form distorted OCs2Mg3 trigonal bipyramids that share corners with three OCsMg5 octahedra, corners with two equivalent OMg5 square pyramids, corners with four OCs2Mg3 trigonal bipyramids, and edges with two equivalent OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–47°. In the seventh O site, O is bonded to three Mg and two equivalent Hf atoms to form OHf2Mg3 trigonal bipyramids that share corners with three OMg5 square pyramids, corners with four OHf2Mg3 trigonal bipyramids, and edges with two equivalent OMg6 octahedra. In the eighth O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with two equivalent OMg6 octahedra, corners with two equivalent OMg5 square pyramids, a cornercorner with one OCs2Mg3 trigonal bipyramid, edges with eight OCsMg5 octahedra, and edges with four OMg5 square pyramids. The corner-sharing octahedral tilt angles are 5°. In the ninth O site, O is bonded to five Mg atoms to form OMg5 square pyramids that share corners with two equivalent OMg6 octahedra, corners with four OMg5 square pyramids, a cornercorner with one OHf2Mg3 trigonal bipyramid, edges with six OMg6 octahedra, and edges with two equivalent OMg5 square pyramids. The corner-sharing octahedral tilt angles are 3°. In the tenth O site, O is bonded in a 5-coordinate geometry to one Cs, three Mg, and one Hf atom. In the eleventh O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with four equivalent OMg6 octahedra, edges with five OCsMg5 octahedra, and edges with six OMg5 square pyramids. The corner-sharing octahedra tilt angles range from 3–12°.