Sr4NbCoO8 is (La,Ba)CuO4-derived structured and crystallizes in the orthorhombic Cmmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 9-coordinate geometry to two equivalent O(2), three equivalent O(1), and four equivalent O(3) atoms. In the second Sr site, Sr(2) is bonded in a 9-coordinate geometry to two equivalent O(1), three equivalent O(2), and four equivalent O(3) atoms. Nb(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form NbO6 octahedra that share corners with four equivalent Co(1)O6 octahedra. The corner-sharing octahedra are not tilted. Co(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form CoO6 octahedra that share corners with four equivalent Nb(1)O6 octahedra. The corner-sharing octahedra are not tilted. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(2), three equivalent Sr(1), and one Co(1) atom to form OSr5Co octahedra that share corners with five equivalent O(1)Sr5Co octahedra, corners with twelve equivalent O(3)Sr4NbCo octahedra, edges with two equivalent O(1)Sr5Co octahedra, edges with six equivalent O(2)Sr5Nb octahedra, and faces with four equivalent O(3)Sr4NbCo octahedra. The corner-sharing octahedral tilt angles range from 0-56°. In the second O site, O(2) is bonded to two equivalent Sr(1), three equivalent Sr(2), and one Nb(1) atom to form distorted OSr5Nb octahedra that share corners with five equivalent O(2)Sr5Nb octahedra, corners with twelve equivalent O(3)Sr4NbCo octahedra, edges with two equivalent O(2)Sr5Nb octahedra, edges with six equivalent O(1)Sr5Co octahedra, and faces with four equivalent O(3)Sr4NbCo octahedra. The corner-sharing octahedral tilt angles range from 0-57°. In the third O site, O(3) is bonded to two equivalent Sr(1), two equivalent Sr(2), one Nb(1), and one Co(1) atom to form distorted OSr4NbCo octahedra that share corners with two equivalent O(3)Sr4NbCo octahedra, corners with six equivalent O(1)Sr5Co octahedra, corners with six equivalent O(2)Sr5Nb octahedra, edges with two equivalent O(3)Sr4NbCo octahedra, faces with two equivalent O(1)Sr5Co octahedra, faces with two equivalent O(2)Sr5Nb octahedra, and faces with four equivalent O(3)Sr4NbCo octahedra. The corner-sharing octahedral tilt angles range from 0-57°.
Sr4NbCoO8 is (La,Ba)CuO4-derived structured and crystallizes in the orthorhombic Cmmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 9-coordinate geometry to two equivalent O(2), three equivalent O(1), and four equivalent O(3) atoms. Both Sr(1)-O(2) bond lengths are 2.79 Å. There is one shorter (2.42 Å) and two longer (2.82 Å) Sr(1)-O(1) bond lengths. All Sr(1)-O(3) bond lengths are 2.75 Å. In the second Sr site, Sr(2) is bonded in a 9-coordinate geometry to two equivalent O(1), three equivalent O(2), and four equivalent O(3) atoms. Both Sr(2)-O(1) bond lengths are 2.80 Å. There is one shorter (2.50 Å) and two longer (2.82 Å) Sr(2)-O(2) bond lengths. All Sr(2)-O(3) bond lengths are 2.72 Å. Nb(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form NbO6 octahedra that share corners with four equivalent Co(1)O6 octahedra. The corner-sharing octahedra are not tilted. Both Nb(1)-O(2) bond lengths are 2.06 Å. All Nb(1)-O(3) bond lengths are 1.98 Å. Co(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form CoO6 octahedra that share corners with four equivalent Nb(1)O6 octahedra. The corner-sharing octahedra are not tilted. Both Co(1)-O(1) bond lengths are 2.09 Å. All Co(1)-O(3) bond lengths are 1.98 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(2), three equivalent Sr(1), and one Co(1) atom to form OSr5Co octahedra that share corners with five equivalent O(1)Sr5Co octahedra, corners with twelve equivalent O(3)Sr4NbCo octahedra, edges with two equivalent O(1)Sr5Co octahedra, edges with six equivalent O(2)Sr5Nb octahedra, and faces with four equivalent O(3)Sr4NbCo octahedra. The corner-sharing octahedral tilt angles range from 0-56°. In the second O site, O(2) is bonded to two equivalent Sr(1), three equivalent Sr(2), and one Nb(1) atom to form distorted OSr5Nb octahedra that share corners with five equivalent O(2)Sr5Nb octahedra, corners with twelve equivalent O(3)Sr4NbCo octahedra, edges with two equivalent O(2)Sr5Nb octahedra, edges with six equivalent O(1)Sr5Co octahedra, and faces with four equivalent O(3)Sr4NbCo octahedra. The corner-sharing octahedral tilt angles range from 0-57°. In the third O site, O(3) is bonded to two equivalent Sr(1), two equivalent Sr(2), one Nb(1), and one Co(1) atom to form distorted OSr4NbCo octahedra that share corners with two equivalent O(3)Sr4NbCo octahedra, corners with six equivalent O(1)Sr5Co octahedra, corners with six equivalent O(2)Sr5Nb octahedra, edges with two equivalent O(3)Sr4NbCo octahedra, faces with two equivalent O(1)Sr5Co octahedra, faces with two equivalent O(2)Sr5Nb octahedra, and faces with four equivalent O(3)Sr4NbCo octahedra. The corner-sharing octahedral tilt angles range from 0-57°.