Materials Data on KBaYSi2O7 by Materials Project
KBaYSi2O7 crystallizes in the monoclinic P2_1/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 2.79–3.19 Å. Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.75–3.09 Å. Y3+ is bonded to six O2- atoms to form YO6 octahedra that share corners with six SiO4 tetrahedra. There are a spread of Y–O bond distances ranging from 2.22–2.34 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent YO6 octahedra and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 20–47°. There are a spread of Si–O bond distances ranging from 1.63–1.69 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent YO6 octahedra and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 10–48°. There are a spread of Si–O bond distances ranging from 1.63–1.69 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, two equivalent Ba2+, one Y3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, two equivalent Ba2+, one Y3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to three equivalent Ba2+, one Y3+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Ba2+, one Y3+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to three equivalent K1+, one Y3+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent K1+ and two Si4+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Ba2+, one Y3+, and one Si4+ atom.