Na2Co3O4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted NaO6 octahedra that share corners with eight equivalent Co(2)O4 tetrahedra, edges with two equivalent Na(1)O6 octahedra, edges with four equivalent Na(2)O6 octahedra, and edges with two equivalent Co(2)O4 tetrahedra. In the second Na site, Na(2) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form distorted NaO6 octahedra that share corners with eight equivalent Co(2)O4 tetrahedra, edges with two equivalent Na(2)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with two equivalent Co(2)O4 tetrahedra. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a distorted see-saw-like geometry to one O(2), one O(3), and two equivalent O(1) atoms. In the second Co site, Co(2) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form distorted CoO4 tetrahedra that share corners with four equivalent Na(1)O6 octahedra, corners with four equivalent Na(2)O6 octahedra, corners with two equivalent Co(2)O4 tetrahedra,  an edgeedge with one Na(1)O6 octahedra,  an edgeedge with one Na(2)O6 octahedra, and  an edgeedge with one Co(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 8-90°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), two equivalent Na(2), one Co(1), and two equivalent Co(2) atoms to form a mixture of distorted edge and corner-sharing ONa3Co3 octahedra. The corner-sharing octahedral tilt angles range from 0-70°. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Na(2), two equivalent Na(1), one Co(1), and two equivalent Co(2) atoms. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), one Co(1), and two equivalent Co(2) atoms to form a mixture of distorted edge and corner-sharing ONa3Co3 octahedra. The corner-sharing octahedral tilt angles range from 0-70°.
Na2Co3O4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted NaO6 octahedra that share corners with eight equivalent Co(2)O4 tetrahedra, edges with two equivalent Na(1)O6 octahedra, edges with four equivalent Na(2)O6 octahedra, and edges with two equivalent Co(2)O4 tetrahedra. Both Na(1)-O(1) bond lengths are 2.41 Å. Both Na(1)-O(2) bond lengths are 2.59 Å. Both Na(1)-O(3) bond lengths are 2.60 Å. In the second Na site, Na(2) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form distorted NaO6 octahedra that share corners with eight equivalent Co(2)O4 tetrahedra, edges with two equivalent Na(2)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with two equivalent Co(2)O4 tetrahedra. The Na(2)-O(2) bond length is 2.72 Å. The Na(2)-O(3) bond length is 2.57 Å. There are two shorter (2.54 Å) and two longer (2.61 Å) Na(2)-O(1) bond lengths. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a distorted see-saw-like geometry to one O(2), one O(3), and two equivalent O(1) atoms. The Co(1)-O(2) bond length is 1.99 Å. The Co(1)-O(3) bond length is 1.96 Å. Both Co(1)-O(1) bond lengths are 2.06 Å. In the second Co site, Co(2) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form distorted CoO4 tetrahedra that share corners with four equivalent Na(1)O6 octahedra, corners with four equivalent Na(2)O6 octahedra, corners with two equivalent Co(2)O4 tetrahedra,  an edgeedge with one Na(1)O6 octahedra,  an edgeedge with one Na(2)O6 octahedra, and  an edgeedge with one Co(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 8-90°. The Co(2)-O(2) bond length is 2.12 Å. The Co(2)-O(3) bond length is 2.00 Å. There is one shorter (1.98 Å) and one longer (1.99 Å) Co(2)-O(1) bond length. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), two equivalent Na(2), one Co(1), and two equivalent Co(2) atoms to form a mixture of distorted edge and corner-sharing ONa3Co3 octahedra. The corner-sharing octahedral tilt angles range from 0-70°. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Na(2), two equivalent Na(1), one Co(1), and two equivalent Co(2) atoms. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), one Co(1), and two equivalent Co(2) atoms to form a mixture of distorted edge and corner-sharing ONa3Co3 octahedra. The corner-sharing octahedral tilt angles range from 0-70°.