Materials Data on CsHfMg6O7 by Materials Project
CsMg6HfO7 crystallizes in the tetragonal P4mm space group. The structure is two-dimensional and consists of one CsMg6HfO7 sheet oriented in the (0, 0, 1) direction. Cs is bonded in a distorted square co-planar geometry to four equivalent O atoms. All Cs–O bond lengths are 3.00 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to five O atoms to form a mixture of distorted edge and corner-sharing MgO5 trigonal bipyramids. There are one shorter (1.98 Å) and four longer (2.11 Å) Mg–O bond lengths. In the second Mg site, Mg is bonded to five O atoms to form a mixture of distorted edge and corner-sharing MgO5 trigonal bipyramids. There are one shorter (2.04 Å) and four longer (2.12 Å) Mg–O bond lengths. In the third Mg site, Mg is bonded in a single-bond geometry to one O atom. The Mg–O bond length is 2.03 Å. In the fourth Mg site, Mg is bonded to five O atoms to form a mixture of distorted edge and corner-sharing MgO5 trigonal bipyramids. There are a spread of Mg–O bond distances ranging from 1.99–2.14 Å. Hf is bonded in a 5-coordinate geometry to five O atoms. There are one shorter (1.89 Å) and four longer (2.12 Å) Hf–O bond lengths. There are five inequivalent O sites. In the first O site, O is bonded to five Mg atoms to form distorted corner-sharing OMg5 trigonal bipyramids. In the second O site, O is bonded in a distorted single-bond geometry to four equivalent Cs and one Hf atom. In the third O site, O is bonded in a 5-coordinate geometry to five Mg atoms. In the fourth O site, O is bonded in a 3-coordinate geometry to one Mg and two equivalent Hf atoms. In the fifth O site, O is bonded to five Mg atoms to form a mixture of distorted edge and corner-sharing OMg5 trigonal bipyramids.