Materials Data on CaAl2Si(HO2)4 by Materials Project
CaAl2Si(HO2)4 crystallizes in the tetragonal I4_1/a space group. The structure is three-dimensional. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are four shorter (2.41 Å) and four longer (2.56 Å) Ca–O bond lengths. Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent SiO4 tetrahedra and edges with two equivalent AlO6 octahedra. There is four shorter (1.89 Å) and two longer (1.98 Å) Al–O bond length. Si4+ is bonded to four equivalent O2- atoms to form SiO4 tetrahedra that share corners with four equivalent AlO6 octahedra. The corner-sharing octahedral tilt angles are 45°. 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 0.98 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Al3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Ca2+, two equivalent Al3+, and one H1+ atom.