Materials Data on K2Cr2O7 by Materials Project
K2Cr2O7 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of two K2Cr2O7 sheets oriented in the (1, 0, 0) direction. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of K–O bond distances ranging from 2.63–2.95 Å. In the second K1+ site, K1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of K–O bond distances ranging from 2.59–2.72 Å. There are two inequivalent Cr6+ sites. In the first Cr6+ site, Cr6+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. There are a spread of Cr–O bond distances ranging from 1.63–1.77 Å. In the second Cr6+ site, Cr6+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. There are a spread of Cr–O bond distances ranging from 1.68–1.90 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one Cr6+ atom. In the second O2- site, O2- is bonded in a linear geometry to two Cr6+ atoms. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one Cr6+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two K1+ and one Cr6+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to two K1+ and one Cr6+ atom.