DOE OSTI2020
ZnCrO4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Cr6+ sites. In the first Cr6+ site, Cr6+ is bonded to four O2- atoms to form CrO4 tetrahedra that share corners with six ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 14–62°. There are a spread of Cr–O bond distances ranging from 1.64–1.76 Å. In the second Cr6+ site, Cr6+ is bonded to four O2- atoms to form CrO4 tetrahedra that share corners with six ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 21–56°. There is two shorter (1.64 Å) and two longer (1.71 Å) Cr–O bond length. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with six CrO4 tetrahedra and edges with two equivalent ZnO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.03–2.18 Å. In the second Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with six CrO4 tetrahedra and edges with three ZnO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.07–2.19 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to one Cr6+ and three Zn2+ atoms to form distorted edge-sharing OZn3Cr tetrahedra. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr6+ and one Zn2+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cr6+ and one Zn2+ atom. In the fourth O2- site, O2- is bonded in a distorted linear geometry to one Cr6+ and one Zn2+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cr6+ and two Zn2+ atoms.