Materials Data on K4Yb2Si8O21 by Materials Project
K4Yb2Si8O21 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 6-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.67–3.37 Å. In the second 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 2.92–3.29 Å. Yb3+ is bonded to six O2- atoms to form YbO6 octahedra that share corners with six SiO4 tetrahedra and an edgeedge with one YbO6 octahedra. There are a spread of Yb–O bond distances ranging from 2.27–2.42 Å. There are four 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 YbO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 55°. There is one shorter (1.59 Å) and three longer (1.66 Å) Si–O bond length. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one YbO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 55°. 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 corners with three equivalent YbO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–54°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one YbO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 41°. There are a spread of Si–O bond distances ranging from 1.60–1.66 Å. There are eleven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one K1+, one Yb3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent K1+, one Yb3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent K1+ and two Si4+ atoms. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two K1+, one Yb3+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a distorted 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 two K1+, one Yb3+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent K1+ and two equivalent Si4+ atoms. In the eighth O2- site, O2- is bonded in a linear geometry to one 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 3-coordinate geometry to one K1+, two equivalent Yb3+, and one Si4+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one K1+ and two Si4+ atoms.