DOI: 10.17188/1318571
title: Materials Data on ZnCr2O4 by Materials Project

description: ZnCr2O4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Cr3+ sites. In the first Cr3+ site, Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with four CrO6 octahedra, corners with two equivalent ZnO5 square pyramids, edges with four CrO6 octahedra, and edges with three ZnO5 square pyramids. The corner-sharing octahedra tilt angles range from 49–56°. There are a spread of Cr–O bond distances ranging from 1.95–2.18 Å. In the second Cr3+ site, Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with four CrO6 octahedra, corners with four ZnO5 square pyramids, edges with four CrO6 octahedra, and a faceface with one ZnO5 square pyramid. The corner-sharing octahedra tilt angles range from 49–56°. There are a spread of Cr–O bond distances ranging from 1.94–2.20 Å. In the third Cr3+ site, Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with four CrO6 octahedra, corners with four ZnO5 square pyramids, edges with four CrO6 octahedra, and a faceface with one ZnO5 square pyramid. The corner-sharing octahedra tilt angles range from 49–56°. There are a spread of Cr–O bond distances ranging from 1.94–2.19 Å. In the fourth Cr3+ site, Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with four CrO6 octahedra, corners with two equivalent ZnO5 square pyramids, edges with four CrO6 octahedra, and edges with three ZnO5 square pyramids. The corner-sharing octahedra tilt angles range from 49–56°. There are a spread of Cr–O bond distances ranging from 1.95–2.18 Å. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to five O2- atoms to form ZnO5 square pyramids that share corners with six CrO6 octahedra, edges with three CrO6 octahedra, edges with two equivalent ZnO5 square pyramids, and a faceface with one CrO6 octahedra. The corner-sharing octahedra tilt angles range from 10–58°. There are a spread of Zn–O bond distances ranging from 2.09–2.15 Å. In the second Zn2+ site, Zn2+ is bonded to five O2- atoms to form ZnO5 square pyramids that share corners with six CrO6 octahedra, edges with three CrO6 octahedra, edges with two equivalent ZnO5 square pyramids, and a faceface with one CrO6 octahedra. The corner-sharing octahedra tilt angles range from 10–58°. There are a spread of Zn–O bond distances ranging from 2.09–2.14 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to three Cr3+ and one Zn2+ atom to form OZnCr3 trigonal pyramids that share corners with two equivalent OZn2Cr3 square pyramids, corners with two equivalent OZnCr3 trigonal pyramids, edges with three OZn2Cr3 square pyramids, and edges with two equivalent OZn2Cr3 trigonal bipyramids. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Cr3+ atoms. In the third O2- site, O2- is bonded in a trigonal planar geometry to three Cr3+ atoms. In the fourth O2- site, O2- is bonded to three Cr3+ and one Zn2+ atom to form OZnCr3 trigonal pyramids that share corners with two equivalent OZn2Cr3 square pyramids, a cornercorner with one OZn2Cr3 trigonal bipyramid, corners with two equivalent OZnCr3 trigonal pyramids, and edges with three OZn2Cr3 square pyramids. In the fifth O2- site, O2- is bonded to three Cr3+ and two equivalent Zn2+ atoms to form OZn2Cr3 square pyramids that share corners with two equivalent OZn2Cr3 trigonal bipyramids, corners with two equivalent OZnCr3 trigonal pyramids, edges with four OZn2Cr3 square pyramids, an edgeedge with one OZn2Cr3 trigonal bipyramid, and edges with three OZnCr3 trigonal pyramids. In the sixth O2- site, O2- is bonded in a 5-coordinate geometry to three Cr3+ and two equivalent Zn2+ atoms. In the seventh O2- site, O2- is bonded to three Cr3+ and two equivalent Zn2+ atoms to form OZn2Cr3 square pyramids that share corners with two equivalent OZnCr3 trigonal pyramids, edges with four OZn2Cr3 square pyramids, and edges with three OZnCr3 trigonal pyramids. In the eighth O2- site, O2- is bonded to three Cr3+ and two equivalent Zn2+ atoms to form distorted OZn2Cr3 trigonal bipyramids that share corners with two equivalent OZn2Cr3 square pyramids, a cornercorner with one OZnCr3 trigonal pyramid, an edgeedge with one OZn2Cr3 square pyramid, edges with two equivalent OZn2Cr3 trigonal bipyramids, and edges with two equivalent OZnCr3 trigonal pyramids.