Materials Data on K2Si2O5 by Materials Project
K2Si2O5 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. there are six inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.72–3.20 Å. In the second K1+ site, K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.78–3.23 Å. In the third K1+ site, K1+ is bonded in a 4-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.65–3.24 Å. In the fourth K1+ site, K1+ is bonded to six O2- atoms to form KO6 octahedra that share corners with six SiO4 tetrahedra. There are a spread of K–O bond distances ranging from 2.60–2.81 Å. In the fifth K1+ site, K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.71–3.22 Å. In the sixth K1+ site, K1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.72–3.28 Å. There are six inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one KO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 17°. There are a spread of Si–O bond distances ranging from 1.59–1.68 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one KO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 27°. There are a spread of Si–O bond distances ranging from 1.58–1.68 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one KO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 31°. There is one shorter (1.58 Å) and three longer (1.67 Å) Si–O bond length. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one KO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 1°. There is one shorter (1.59 Å) and three longer (1.67 Å) Si–O bond length. In the fifth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one KO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 15°. There are a spread of Si–O bond distances ranging from 1.58–1.68 Å. In the sixth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one KO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 42°. There is one shorter (1.58 Å) and three longer (1.67 Å) Si–O bond length. There are fifteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two K1+ and two Si4+ atoms. In the second O2- site, O2- is bonded in a distorted single-bond geometry to four K1+ and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to three K1+ and two Si4+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to four K1+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to four K1+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to four K1+ and one Si4+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two Si4+ atoms. In the ninth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two Si4+ atoms. In the tenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to three K1+ and two Si4+ atoms. In the eleventh O2- site, O2- is bonded in a 2-coordinate geometry to two K1+ and two Si4+ atoms. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to three K1+ and one Si4+ atom. In the thirteenth O2- site, O2- is bonded in a distorted single-bond geometry to four K1+ and one Si4+ atom. In the fourteenth O2- site, O2- is bonded in a distorted linear geometry to one K1+ and two Si4+ atoms. In the fifteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two K1+ and two Si4+ atoms.