Materials Data on K2Ce(Si2O5)3 by Materials Project
K2Ce(Si2O5)3 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.77–3.28 Å. Ce4+ is bonded to six O2- atoms to form CeO6 octahedra that share corners with six SiO4 tetrahedra. There are two shorter (2.21 Å) and four longer (2.28 Å) Ce–O bond lengths. There are three 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 CeO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of Si–O bond distances ranging from 1.61–1.66 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one CeO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of Si–O bond distances ranging from 1.61–1.66 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one CeO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. There are a spread of Si–O bond distances ranging from 1.61–1.65 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+ and two Si4+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+ and two equivalent Si4+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one K1+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one K1+ and two Si4+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Ce4+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Ce4+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent K1+, one Ce4+, and one Si4+ atom.