Na3NiO3 crystallizes in the tetragonal P4_2/mnm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1) and four equivalent O(2) atoms. In the second Na site, Na(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted corner-sharing NaO4 tetrahedra. Ni(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(2), four equivalent Na(1), and one Ni(1) atom.
Na3NiO3 crystallizes in the tetragonal P4_2/mnm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1) and four equivalent O(2) atoms. The Na(1)-O(1) bond length is 2.60 Å. There are a spread of Na(1)-O(2) bond distances ranging from 2.24-2.94 Å. In the second Na site, Na(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted corner-sharing NaO4 tetrahedra. Both Na(2)-O(1) bond lengths are 2.34 Å. Both Na(2)-O(2) bond lengths are 2.29 Å. Ni(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Ni(1)-O(1) bond lengths are 1.86 Å. Both Ni(1)-O(2) bond lengths are 1.83 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(2), four equivalent Na(1), and one Ni(1) atom.