Materials Data on ZnCrO2 by Materials Project

Abstract

ZnCrO2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Cr2+ sites. In the first Cr2+ site, Cr2+ is bonded to five O2- atoms to form CrO5 square pyramids that share corners with two equivalent CrO6 octahedra, corners with three ZnO4 tetrahedra, edges with two equivalent CrO6 octahedra, and edges with two equivalent CrO5 square pyramids. The corner-sharing octahedra tilt angles range from 48–51°. There are a spread of Cr–O bond distances ranging from 1.99–2.13 Å. In the second Cr2+ site, Cr2+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with two equivalent CrO6 octahedra, corners with two equivalent CrO5 square pyramids, corners with four ZnO4 tetrahedra, and edges with two equivalent CrO6 octahedra. The corner-sharing octahedra tilt angles range from 49–52°. There are a spread of Cr–O bond distances ranging from 2.00–2.11 Å. In the third Cr2+ site, Cr2+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of Cr–O bond distances ranging from 2.01–2.08 Å. In the fourth Cr2+ site, Cr2+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with two equivalent CrO6 octahedra, corners with three ZnO4 tetrahedra, edges with two equivalent CrO6 octahedra, and edges with two equivalent CrO5 square pyramids. The corner-sharing octahedra tilt angles range from 49–52°. There are a spread of Cr–O bond distances ranging from 2.02–2.17 Å. There are four inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to four O2- atoms to form distorted ZnO4 tetrahedra that share corners with four CrO6 octahedra, a cornercorner with one CrO5 square pyramid, and corners with four ZnO4 tetrahedra. The corner-sharing octahedra tilt angles range from 49–68°. There are a spread of Zn–O bond distances ranging from 1.97–2.06 Å. In the second Zn2+ site, Zn2+ is bonded to four O2- atoms to form distorted ZnO4 tetrahedra that share corners with three CrO6 octahedra, corners with two equivalent CrO5 square pyramids, and corners with four ZnO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–64°. There are a spread of Zn–O bond distances ranging from 1.96–2.18 Å. In the third Zn2+ site, Zn2+ is bonded in a 2-coordinate geometry to two O2- atoms. There are one shorter (1.97 Å) and one longer (2.34 Å) Zn–O bond lengths. In the fourth Zn2+ site, Zn2+ is bonded in a 2-coordinate geometry to three O2- atoms. There are a spread of Zn–O bond distances ranging from 2.00–2.60 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to three Cr2+ and two equivalent Zn2+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to four Zn2+ atoms. In the third O2- site, O2- is bonded to three Cr2+ and one Zn2+ atom to form distorted OZnCr3 trigonal pyramids that share a cornercorner with one OZn2Cr3 square pyramid, corners with two equivalent OZnCr3 tetrahedra, corners with six OZnCr3 trigonal pyramids, and an edgeedge with one OZnCr3 tetrahedra. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to three Cr2+ atoms. In the fifth O2- site, O2- is bonded to three Cr2+ and two Zn2+ atoms to form distorted OZn2Cr3 square pyramids that share corners with two equivalent OZn2Cr3 square pyramids, corners with three OZnCr3 trigonal pyramids, and edges with two equivalent OZnCr3 trigonal pyramids. In the sixth O2- site, O2- is bonded to three Cr2+ and one Zn2+ atom to form a mixture of corner and edge-sharing OZnCr3 tetrahedra. In the seventh O2- site, O2- is bonded to three Cr2+ and one Zn2+ atom to form OZnCr3 trigonal pyramids that share a cornercorner with one OZnCr3 tetrahedra, corners with four OZnCr3 trigonal pyramids, and edges with two equivalent OZn2Cr3 square pyramids. In the eighth O2- site, O2- is bonded to two Cr2+ and two equivalent Zn2+ atoms to form distorted OZn2Cr2 trigonal pyramids that share corners with two equivalent OZn2Cr3 square pyramids, a cornercorner with one OZnCr3 tetrahedra, corners with four OZnCr3 trigonal pyramids, and an edgeedge with one OZnCr3 tetrahedra.