DOI: 10.17188/1318611
title: Materials Data on Ca(NiO2)2 by Materials Project

description: Ca(NiO2)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.41 Å. In the second Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.40 Å. There are four inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to five O2- atoms to form NiO5 square pyramids that share corners with four NiO6 octahedra and edges with two equivalent NiO5 square pyramids. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Ni–O bond distances ranging from 1.94–2.02 Å. In the second Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four NiO5 square pyramids and edges with four NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.90–2.03 Å. In the third Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four NiO5 square pyramids and edges with four NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.91–2.05 Å. In the fourth Ni3+ site, Ni3+ is bonded to five O2- atoms to form NiO5 square pyramids that share corners with four NiO6 octahedra and edges with two equivalent NiO5 square pyramids. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Ni–O bond distances ranging from 1.93–2.04 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ni3+ atoms. In the second O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 tetrahedra that share corners with two equivalent OCa2Ni3 square pyramids, corners with two equivalent OCaNi3 tetrahedra, and edges with three OCa2Ni3 square pyramids. In the third O2- site, O2- is bonded to one Ca2+ and three Ni3+ atoms to form distorted OCaNi3 trigonal pyramids that share corners with two equivalent OCa2Ni3 square pyramids, corners with two equivalent OCaNi3 trigonal pyramids, and edges with three OCa2Ni3 square pyramids. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ni3+ atoms. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Ca2+ and two equivalent Ni3+ atoms. In the sixth O2- site, O2- is bonded to two equivalent Ca2+ and three Ni3+ atoms to form distorted OCa2Ni3 square pyramids that share corners with two equivalent OCaNi3 trigonal pyramids, edges with four OCa2Ni3 square pyramids, edges with two equivalent OCaNi3 tetrahedra, and an edgeedge with one OCaNi3 trigonal pyramid. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Ca2+ and two equivalent Ni3+ atoms. In the eighth O2- site, O2- is bonded to two equivalent Ca2+ and three Ni3+ atoms to form distorted OCa2Ni3 square pyramids that share corners with two equivalent OCaNi3 tetrahedra, edges with four OCa2Ni3 square pyramids, an edgeedge with one OCaNi3 tetrahedra, and edges with two equivalent OCaNi3 trigonal pyramids.