DOE OSTI2020
Zn(NiO2)2 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are four inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four NiO6 octahedra, corners with two equivalent ZnO5 square pyramids, edges with four NiO6 octahedra, and edges with three ZnO5 square pyramids. The corner-sharing octahedra tilt angles range from 50–58°. There are a spread of Ni–O bond distances ranging from 1.85–2.10 Å. In the second Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four NiO6 octahedra, corners with four ZnO5 square pyramids, edges with four NiO6 octahedra, and a faceface with one ZnO5 square pyramid. The corner-sharing octahedra tilt angles range from 50–57°. There are a spread of Ni–O bond distances ranging from 1.91–2.22 Å. In the third Ni3+ site, Ni3+ is bonded to six O2- atoms to form distorted NiO6 octahedra that share corners with four NiO6 octahedra, corners with four ZnO5 square pyramids, edges with four NiO6 octahedra, and a faceface with one ZnO5 square pyramid. The corner-sharing octahedra tilt angles range from 50–58°. There are a spread of Ni–O bond distances ranging from 1.92–2.30 Å. In the fourth Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four NiO6 octahedra, corners with two equivalent ZnO5 square pyramids, edges with four NiO6 octahedra, and edges with three ZnO5 square pyramids. The corner-sharing octahedra tilt angles range from 50–57°. There are a spread of Ni–O bond distances ranging from 1.86–2.09 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 NiO6 octahedra, edges with three NiO6 octahedra, edges with two equivalent ZnO5 square pyramids, and a faceface with one NiO6 octahedra. The corner-sharing octahedra tilt angles range from 11–58°. There are a spread of Zn–O bond distances ranging from 2.04–2.14 Å. In the second Zn2+ site, Zn2+ is bonded to five O2- atoms to form ZnO5 square pyramids that share corners with six NiO6 octahedra, edges with three NiO6 octahedra, edges with two equivalent ZnO5 square pyramids, and a faceface with one NiO6 octahedra. The corner-sharing octahedra tilt angles range from 12–55°. There are a spread of Zn–O bond distances ranging from 2.03–2.12 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to three Ni3+ and one Zn2+ atom to form OZnNi3 trigonal pyramids that share corners with two equivalent OZn2Ni3 square pyramids, corners with two equivalent OZnNi3 trigonal pyramids, and edges with three OZn2Ni3 square pyramids. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Ni3+ atoms. In the third O2- site, O2- is bonded in a trigonal planar geometry to three Ni3+ atoms. In the fourth O2- site, O2- is bonded to three Ni3+ and one Zn2+ atom to form OZnNi3 trigonal pyramids that share corners with two equivalent OZn2Ni3 square pyramids, corners with two equivalent OZnNi3 trigonal pyramids, and edges with three OZn2Ni3 square pyramids. In the fifth O2- site, O2- is bonded to three Ni3+ and two equivalent Zn2+ atoms to form OZn2Ni3 square pyramids that share corners with two equivalent OZnNi3 trigonal pyramids, edges with four OZn2Ni3 square pyramids, and edges with three OZnNi3 trigonal pyramids. In the sixth O2- site, O2- is bonded in a 5-coordinate geometry to three Ni3+ and two equivalent Zn2+ atoms. In the seventh O2- site, O2- is bonded to three Ni3+ and two equivalent Zn2+ atoms to form OZn2Ni3 square pyramids that share corners with two equivalent OZnNi3 trigonal pyramids, edges with four OZn2Ni3 square pyramids, and edges with three OZnNi3 trigonal pyramids. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to three Ni3+ and two equivalent Zn2+ atoms.