Materials Data on KCaSiHO4 by Materials Project
KCaSiHO4 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. K1+ is bonded in a 10-coordinate geometry to two equivalent H1+ and eight O2- atoms. There are one shorter (2.56 Å) and one longer (2.63 Å) K–H bond lengths. There are a spread of K–O bond distances ranging from 2.60–3.28 Å. Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six equivalent SiO4 tetrahedra and edges with two equivalent CaO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.32–2.57 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six equivalent CaO6 octahedra. The corner-sharing octahedra tilt angles range from 36–54°. There are a spread of Si–O bond distances ranging from 1.64–1.72 Å. H1+ is bonded in a distorted linear geometry to two equivalent K1+ and two O2- atoms. There is one shorter (1.04 Å) and one longer (1.57 Å) H–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent K1+, two equivalent Ca2+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent K1+, two equivalent Ca2+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Ca2+, one Si4+, and one H1+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent K1+, one Ca2+, one Si4+, and one H1+ atom.