Materials Data on Ca2Ga2Si(HO4)2 by Materials Project

Abstract

Ca2Ga2Si(HO4)2 crystallizes in the tetragonal I-4 space group. The structure is three-dimensional. Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two SiO4 tetrahedra, corners with four equivalent GaO4 tetrahedra, and edges with three equivalent CaO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.30–2.52 Å. Ga3+ is bonded to four O2- atoms to form GaO4 tetrahedra that share corners with four equivalent CaO6 octahedra, corners with two equivalent GaO4 tetrahedra, and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 63–69°. There are a spread of Ga–O bond distances ranging from 1.84–1.89 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four equivalent O2- atoms to form SiO4 tetrahedra that share corners with four equivalent CaO6 octahedra and corners with four equivalent GaO4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. All Si–O bond lengths are 1.65 Å. In the second Si4+ site, Si4+ is bonded to four equivalent O2- atoms to form SiO4 tetrahedra that share corners with four equivalent CaO6 octahedra and corners with four equivalent GaO4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. All Si–O bond lengths are 1.65 Å. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Ga3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a trigonal planar geometry to one Ca2+ and two equivalent Ga3+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Ga3+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent Ca2+ and one H1+ atom.