Materials Data on Li2Cr2Si2O7 by Materials Project
Li2Cr2Si2O7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 1.98–2.65 Å. In the second Li1+ site, Li1+ is bonded in a 4-coordinate geometry to five O2- atoms. There are a spread of Li–O bond distances ranging from 2.09–2.68 Å. There are two inequivalent Cr2+ sites. In the first Cr2+ site, Cr2+ is bonded to six O2- atoms to form distorted CrO6 octahedra that share corners with three SiO4 tetrahedra, an edgeedge with one CrO6 octahedra, and edges with two equivalent SiO4 tetrahedra. There are a spread of Cr–O bond distances ranging from 2.04–2.52 Å. In the second Cr2+ site, Cr2+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Cr–O bond distances ranging from 2.05–2.19 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 a cornercorner with one CrO6 octahedra, a cornercorner with one SiO4 tetrahedra, and edges with two equivalent CrO6 octahedra. The corner-sharing octahedral tilt angles are 59°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent CrO6 octahedra and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–58°. There are a spread of Si–O bond distances ranging from 1.63–1.67 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Li1+, one Cr2+, and two Si4+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Li1+, one Cr2+, and one Si4+ atom. In the third O2- site, O2- is bonded to three Cr2+ and one Si4+ atom to form distorted OCr3Si tetrahedra that share a cornercorner with one OLi2CrSi tetrahedra and an edgeedge with one OCr3Si tetrahedra. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two Li1+, one Cr2+, and one Si4+ atom. In the fifth O2- site, O2- is bonded to two Li1+, one Cr2+, and one Si4+ atom to form corner-sharing OLi2CrSi tetrahedra. In the sixth O2- site, O2- is bonded in a trigonal planar geometry to one Li1+, one Cr2+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to one Li1+, two Cr2+, and one Si4+ atom.