Materials Data on K3NaCr2O8 by Materials Project

Abstract

K3Na(CrO4)2 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 1-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.60–3.32 Å. In the second K1+ site, K1+ is bonded in a 10-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.93–3.29 Å. Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with six equivalent CrO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.39–2.41 Å. Cr6+ is bonded to four O2- atoms to form CrO4 tetrahedra that share corners with three equivalent NaO6 octahedra. The corner-sharing octahedra tilt angles range from 14–24°. There are a spread of Cr–O bond distances ranging from 1.64–1.68 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to four K1+, one Na1+, and one Cr6+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to four K1+, one Na1+, and one Cr6+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two K1+ and one Cr6+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to four K1+, one Na1+, and one Cr6+ atom.