Materials Data on KCa4Si8H16O28F by Materials Project
KCa4Si8H16O28F crystallizes in the tetragonal P4/mnc space group. The structure is three-dimensional. K1+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All K–O bond lengths are 3.00 Å. Ca2+ is bonded to six O2- and one F1- atom to form distorted CaO6F pentagonal bipyramids that share a cornercorner with one CaO6F pentagonal bipyramid, corners with four equivalent SiO4 tetrahedra, and faces with two equivalent CaO6F pentagonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.42–2.52 Å. The Ca–F bond length is 2.44 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent CaO6F pentagonal bipyramids and corners with three equivalent SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.61–1.65 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Si4+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Si4+ atoms. In the third O2- site, O2- is bonded in a distorted water-like geometry to one K1+, one Ca2+, and two H1+ atoms. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ca2+ and one Si4+ atom. F1- is bonded in a square co-planar geometry to four equivalent Ca2+ atoms.