Materials Data on Na4Ni2O5 by Materials Project
Na4Ni2O5 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.37–3.01 Å. In the second Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 trigonal bipyramids that share corners with three NiO4 tetrahedra, edges with two equivalent NiO4 tetrahedra, and an edgeedge with one NaO5 trigonal bipyramid. There are a spread of Na–O bond distances ranging from 2.40–2.58 Å. In the third Na1+ site, Na1+ is bonded in a 5-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.27–2.98 Å. In the fourth Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Na–O bond distances ranging from 2.26–2.50 Å. There are two inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with three NiO4 tetrahedra, a cornercorner with one NaO5 trigonal bipyramid, and edges with two equivalent NaO5 trigonal bipyramids. There are a spread of Ni–O bond distances ranging from 1.82–1.90 Å. In the second Ni3+ site, Ni3+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with three NiO4 tetrahedra and corners with two equivalent NaO5 trigonal bipyramids. There are a spread of Ni–O bond distances ranging from 1.80–1.89 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to five Na1+ and one Ni3+ atom to form a mixture of distorted corner and edge-sharing ONa5Ni octahedra. The corner-sharing octahedra tilt angles range from 42–51°. In the second O2- site, O2- is bonded in a 5-coordinate geometry to five Na1+ and two equivalent Ni3+ atoms. In the third O2- site, O2- is bonded to five Na1+ and one Ni3+ atom to form a mixture of corner and edge-sharing ONa5Ni octahedra. The corner-sharing octahedra tilt angles range from 42–51°. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to three Na1+ and two equivalent Ni3+ atoms. In the fifth O2- site, O2- is bonded in a 6-coordinate geometry to four Na1+ and two Ni3+ atoms.