Ba2CoO4 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one O(4), two equivalent O(2), three equivalent O(1), and three equivalent O(3) atoms. Co(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 1-coordinate geometry to two equivalent Ba(1), three equivalent Ba(2), and one Co(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), and one Co(1) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to two equivalent Ba(1), three equivalent Ba(2), and one Co(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ba(2), two equivalent Ba(1), and one Co(1) atom.
Ba2CoO4 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There is one shorter (2.78 Å) and one longer (2.81 Å) Ba(1)-O(1) bond length. There is one shorter (2.71 Å) and one longer (2.87 Å) Ba(1)-O(2) bond length. There is one shorter (2.69 Å) and one longer (2.75 Å) Ba(1)-O(3) bond length. There is one shorter (2.79 Å) and one longer (2.94 Å) Ba(1)-O(4) bond length. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one O(4), two equivalent O(2), three equivalent O(1), and three equivalent O(3) atoms. The Ba(2)-O(4) bond length is 2.64 Å. There is one shorter (2.77 Å) and one longer (2.92 Å) Ba(2)-O(2) bond length. There are a spread of Ba(2)-O(1) bond distances ranging from 2.73-3.29 Å. There are a spread of Ba(2)-O(3) bond distances ranging from 2.98-3.32 Å. Co(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Co(1)-O(1) bond length is 1.81 Å. The Co(1)-O(2) bond length is 1.80 Å. The Co(1)-O(3) bond length is 1.78 Å. The Co(1)-O(4) bond length is 1.78 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 1-coordinate geometry to two equivalent Ba(1), three equivalent Ba(2), and one Co(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), and one Co(1) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to two equivalent Ba(1), three equivalent Ba(2), and one Co(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ba(2), two equivalent Ba(1), and one Co(1) atom.