Materials Data on Li2Cr2O7 by Materials Project

Abstract

Li2Cr2O7 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with four equivalent CrO4 tetrahedra, edges with two equivalent LiO6 octahedra, and edges with two equivalent LiO6 pentagonal pyramids. There are a spread of Li–O bond distances ranging from 2.15–2.27 Å. In the second Li1+ site, Li1+ is bonded to six O2- atoms to form distorted LiO6 pentagonal pyramids that share corners with three equivalent CrO4 tetrahedra and edges with two equivalent LiO6 octahedra. There are a spread of Li–O bond distances ranging from 2.05–2.37 Å. There are two inequivalent Cr6+ sites. In the first Cr6+ site, Cr6+ is bonded in a 4-coordinate geometry to six O2- atoms. There are a spread of Cr–O bond distances ranging from 1.62–2.30 Å. In the second Cr6+ site, Cr6+ is bonded to four O2- atoms to form CrO4 tetrahedra that share corners with four equivalent LiO6 octahedra and corners with three equivalent LiO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 53–60°. There are a spread of Cr–O bond distances ranging from 1.65–1.68 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two Li1+ and one Cr6+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+ and two Cr6+ atoms. In the third O2- site, O2- is bonded to three Li1+ and one Cr6+ atom to form distorted edge-sharing OLi3Cr tetrahedra. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+ and two equivalent Cr6+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Li1+ and one Cr6+ atom.