DOE OSTI2020
ZnCo2O4 is Spinel-like structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are twelve inequivalent Co3+ sites. In the first Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with three CoO4 tetrahedra, corners with three ZnO4 tetrahedra, edges with two equivalent ZnO6 octahedra, and edges with four CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.92–1.97 Å. In the second Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with three equivalent CoO4 tetrahedra, corners with three equivalent ZnO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.91–1.97 Å. In the third Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with six CoO6 octahedra and corners with six ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 53–61°. There are a spread of Co–O bond distances ranging from 1.87–1.93 Å. In the fourth Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent ZnO4 tetrahedra, corners with four CoO4 tetrahedra, edges with three CoO6 octahedra, and edges with three ZnO6 octahedra. There are a spread of Co–O bond distances ranging from 1.90–1.98 Å. In the fifth Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with three ZnO6 octahedra and corners with nine CoO6 octahedra. The corner-sharing octahedra tilt angles range from 57–63°. There are a spread of Co–O bond distances ranging from 1.94–2.01 Å. In the sixth Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with six CoO6 octahedra and corners with six ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 53–62°. There is two shorter (1.87 Å) and two longer (1.92 Å) Co–O bond length. In the seventh Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six CoO4 tetrahedra, edges with two equivalent CoO6 octahedra, and edges with four ZnO6 octahedra. There are a spread of Co–O bond distances ranging from 1.91–1.96 Å. In the eighth Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with six CoO6 octahedra and corners with six ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 53–61°. There are a spread of Co–O bond distances ranging from 1.87–1.93 Å. In the ninth Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share a cornercorner with one ZnO4 tetrahedra, corners with five CoO4 tetrahedra, edges with three CoO6 octahedra, and edges with three ZnO6 octahedra. There are a spread of Co–O bond distances ranging from 1.91–1.98 Å. In the tenth Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with six CoO6 octahedra and corners with six ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 53–61°. There are a spread of Co–O bond distances ranging from 1.87–1.94 Å. In the eleventh Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with three equivalent CoO4 tetrahedra, corners with three equivalent ZnO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.91–1.97 Å. In the twelfth Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with three ZnO6 octahedra and corners with nine CoO6 octahedra. The corner-sharing octahedra tilt angles range from 57–63°. There is three shorter (1.95 Å) and one longer (2.03 Å) Co–O bond length. There are eight inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with three ZnO6 octahedra and corners with nine CoO6 octahedra. The corner-sharing octahedra tilt angles range from 57–63°. There are three shorter (1.96 Å) and one longer (2.04 Å) Zn–O bond lengths. In the second Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with three CoO4 tetrahedra, corners with three ZnO4 tetrahedra, and edges with six CoO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.05–2.07 Å. In the third Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with three ZnO6 octahedra and corners with nine CoO6 octahedra. The corner-sharing octahedra tilt angles range from 58–63°. There are a spread of Zn–O bond distances ranging from 1.96–2.05 Å. In the fourth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with two equivalent ZnO4 tetrahedra, corners with four CoO4 tetrahedra, an edgeedge with one ZnO6 octahedra, and edges with five CoO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.03–2.12 Å. In the fifth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with six CoO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four equivalent CoO6 octahedra. There are four shorter (2.05 Å) and two longer (2.10 Å) Zn–O bond lengths. In the sixth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with six CoO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four CoO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.05–2.11 Å. In the seventh Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share a cornercorner with one ZnO4 tetrahedra, corners with five CoO4 tetrahedra, an edgeedge with one ZnO6 octahedra, and edges with five CoO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.05–2.09 Å. In the eighth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with six CoO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four CoO6 octahedra. There are four shorter (2.06 Å) and two longer (2.11 Å) Zn–O bond lengths. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Co3+ and two Zn2+ atoms. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Co3+ and two Zn2+ atoms. In the third O2- site, O2- is bonded to three Co3+ and one Zn2+ atom to form distorted OZnCo3 trigonal pyramids that share a cornercorner with one OZn2Co2 tetrahedra and corners with three OCo4 trigonal pyramids. In the fourth O2- site, O2- is bonded to four Co3+ atoms to form distorted corner-sharing OCo4 trigonal pyramids. In the fifth O2- site, O2- is bonded to two Co3+ and two Zn2+ atoms to form a mixture of distorted edge and corner-sharing OZn2Co2 trigonal pyramids. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Co3+ and one Zn2+ atom. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co3+ and one Zn2+ atom. In the eighth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Co3+ and one Zn2+ atom. In the ninth O2- site, O2- is bonded to three Co3+ and one Zn2+ atom to form distorted OZnCo3 trigonal pyramids that share corners with five OZnCo3 trigonal pyramids and edges with two equivalent OZn2Co2 trigonal pyramids. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Co3+ and two Zn2+ atoms. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co3+ and one Zn2+ atom. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Co3+ and two Zn2+ atoms. In the thirteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co3+ and one Zn2+ atom. In the fourteenth O2- site, O2- is bonded to three Co3+ and one Zn2+ atom to form distorted corner-sharing OZnCo3 trigonal pyramids. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co3+ and one Zn2+ atom. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co3+ and one Zn2+ atom. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Co3+ and two Zn2+ atoms. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Co3+ and two Zn2+ atoms. In the nineteenth O2- site, O2- is bonded to two equivalent Co3+ and two Zn2+ atoms to form distorted corner-sharing OZn2Co2 tetrahedra. In the twentieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co3+ and one Zn2+ atom. In the twenty-first O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co3+ and one Zn2+ atom. In the twenty-second O2- site, O2- is bonded to four Co3+ atoms to form distorted OCo4 trigonal pyramids that share corners with two equivalent OZn2Co2 tetrahedra and a cornercorner with one OZnCo3 trigonal pyramid. In the twenty-third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Co3+ and one Zn2+ atom. In the twenty-fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co3+ and one Zn2+ atom.