Na3CrO4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form NaO4 tetrahedra that share corners with four equivalent Na(1)O4 tetrahedra, corners with four equivalent Cr(1)O4 tetrahedra, corners with two equivalent Na(2)O4 trigonal pyramids, and  an edgeedge with one Na(2)O4 trigonal pyramid. In the second Na site, Na(2) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form NaO4 trigonal pyramids that share corners with four equivalent Na(1)O4 tetrahedra, corners with four equivalent Cr(1)O4 tetrahedra, and edges with two equivalent Na(1)O4 tetrahedra. Cr(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form CrO4 tetrahedra that share corners with eight equivalent Na(1)O4 tetrahedra and corners with four equivalent Na(2)O4 trigonal pyramids. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Na(2), two equivalent Na(1), and one Cr(1) atom to form corner-sharing ONa3Cr tetrahedra. In the second O site, O(2) is bonded to one Na(2), two equivalent Na(1), and one Cr(1) atom to form a mixture of distorted corner and edge-sharing ONa3Cr trigonal pyramids. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), and one Cr(1) atom to form a mixture of distorted corner and edge-sharing ONa3Cr trigonal pyramids.
Na3CrO4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form NaO4 tetrahedra that share corners with four equivalent Na(1)O4 tetrahedra, corners with four equivalent Cr(1)O4 tetrahedra, corners with two equivalent Na(2)O4 trigonal pyramids, and  an edgeedge with one Na(2)O4 trigonal pyramid. The Na(1)-O(1) bond length is 2.21 Å. The Na(1)-O(3) bond length is 2.26 Å. There is one shorter (2.27 Å) and one longer (2.31 Å) Na(1)-O(2) bond length. In the second Na site, Na(2) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form NaO4 trigonal pyramids that share corners with four equivalent Na(1)O4 tetrahedra, corners with four equivalent Cr(1)O4 tetrahedra, and edges with two equivalent Na(1)O4 tetrahedra. The Na(2)-O(1) bond length is 2.24 Å. The Na(2)-O(3) bond length is 2.36 Å. Both Na(2)-O(2) bond lengths are 2.33 Å. Cr(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form CrO4 tetrahedra that share corners with eight equivalent Na(1)O4 tetrahedra and corners with four equivalent Na(2)O4 trigonal pyramids. The Cr(1)-O(1) bond length is 1.70 Å. The Cr(1)-O(3) bond length is 1.71 Å. Both Cr(1)-O(2) bond lengths are 1.71 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Na(2), two equivalent Na(1), and one Cr(1) atom to form corner-sharing ONa3Cr tetrahedra. In the second O site, O(2) is bonded to one Na(2), two equivalent Na(1), and one Cr(1) atom to form a mixture of distorted corner and edge-sharing ONa3Cr trigonal pyramids. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), and one Cr(1) atom to form a mixture of distorted corner and edge-sharing ONa3Cr trigonal pyramids.