Li4Fe3CoO8 is Caswellsilverite-derived structured and crystallizes in the monoclinic C2/m space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form LiO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra, corners with three equivalent Co(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Co(1)O6 octahedra, edges with two equivalent Li(1)O6 octahedra, edges with four equivalent Li(2)O6 octahedra, and edges with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-7°. In the second Li site, Li(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form LiO6 octahedra that share corners with six equivalent Fe(1)O6 octahedra, edges with two equivalent Li(2)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with four equivalent Li(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-7°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with six equivalent Li(2)O6 octahedra, edges with two equivalent Li(2)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with four equivalent Li(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-7°. In the second Fe site, Fe(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form FeO6 octahedra that share corners with six equivalent Li(1)O6 octahedra, edges with two equivalent Li(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with four equivalent Li(2)O6 octahedra, and edges with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. Co(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form CoO6 octahedra that share corners with six equivalent Li(1)O6 octahedra, edges with two equivalent Li(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with four equivalent Li(2)O6 octahedra, and edges with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-4°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Li(2), two equivalent Li(1), one Fe(1), one Fe(2), and one Co(1) atom to form OLi3Fe2Co octahedra that share corners with six equivalent O(1)Li3Fe2Co octahedra, edges with four equivalent O(1)Li3Fe2Co octahedra, edges with four equivalent O(3)Li3Fe2Co octahedra, and edges with four equivalent O(2)Li3Fe3 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the second O site, O(2) is bonded to one Li(1), two equivalent Li(2), one Fe(2), and two equivalent Fe(1) atoms to form OLi3Fe3 octahedra that share corners with three equivalent O(3)Li3Fe2Co octahedra, corners with three equivalent O(2)Li3Fe3 octahedra,  an edgeedge with one O(2)Li3Fe3 octahedra, edges with three equivalent O(3)Li3Fe2Co octahedra, and edges with eight equivalent O(1)Li3Fe2Co octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the third O site, O(3) is bonded to one Li(1), two equivalent Li(2), two equivalent Fe(1), and one Co(1) atom to form OLi3Fe2Co octahedra that share corners with three equivalent O(3)Li3Fe2Co octahedra, corners with three equivalent O(2)Li3Fe3 octahedra,  an edgeedge with one O(3)Li3Fe2Co octahedra, edges with three equivalent O(2)Li3Fe3 octahedra, and edges with eight equivalent O(1)Li3Fe2Co octahedra. The corner-sharing octahedral tilt angles range from 0-6°.
Li4Fe3CoO8 is Caswellsilverite-derived structured and crystallizes in the monoclinic C2/m space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form LiO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra, corners with three equivalent Co(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Co(1)O6 octahedra, edges with two equivalent Li(1)O6 octahedra, edges with four equivalent Li(2)O6 octahedra, and edges with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-7°. The Li(1)-O(2) bond length is 2.07 Å. The Li(1)-O(3) bond length is 2.30 Å. There are two shorter (2.07 Å) and two longer (2.28 Å) Li(1)-O(1) bond lengths. In the second Li site, Li(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form LiO6 octahedra that share corners with six equivalent Fe(1)O6 octahedra, edges with two equivalent Li(2)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with four equivalent Li(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-7°. Both Li(2)-O(1) bond lengths are 2.15 Å. Both Li(2)-O(2) bond lengths are 2.15 Å. Both Li(2)-O(3) bond lengths are 2.14 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with six equivalent Li(2)O6 octahedra, edges with two equivalent Li(2)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with four equivalent Li(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-7°. Both Fe(1)-O(1) bond lengths are 2.04 Å. Both Fe(1)-O(2) bond lengths are 2.05 Å. Both Fe(1)-O(3) bond lengths are 2.04 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form FeO6 octahedra that share corners with six equivalent Li(1)O6 octahedra, edges with two equivalent Li(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, edges with four equivalent Li(2)O6 octahedra, and edges with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. Both Fe(2)-O(2) bond lengths are 2.05 Å. All Fe(2)-O(1) bond lengths are 2.05 Å. Co(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form CoO6 octahedra that share corners with six equivalent Li(1)O6 octahedra, edges with two equivalent Li(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with four equivalent Li(2)O6 octahedra, and edges with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-4°. Both Co(1)-O(3) bond lengths are 1.97 Å. All Co(1)-O(1) bond lengths are 1.97 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Li(2), two equivalent Li(1), one Fe(1), one Fe(2), and one Co(1) atom to form OLi3Fe2Co octahedra that share corners with six equivalent O(1)Li3Fe2Co octahedra, edges with four equivalent O(1)Li3Fe2Co octahedra, edges with four equivalent O(3)Li3Fe2Co octahedra, and edges with four equivalent O(2)Li3Fe3 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the second O site, O(2) is bonded to one Li(1), two equivalent Li(2), one Fe(2), and two equivalent Fe(1) atoms to form OLi3Fe3 octahedra that share corners with three equivalent O(3)Li3Fe2Co octahedra, corners with three equivalent O(2)Li3Fe3 octahedra,  an edgeedge with one O(2)Li3Fe3 octahedra, edges with three equivalent O(3)Li3Fe2Co octahedra, and edges with eight equivalent O(1)Li3Fe2Co octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the third O site, O(3) is bonded to one Li(1), two equivalent Li(2), two equivalent Fe(1), and one Co(1) atom to form OLi3Fe2Co octahedra that share corners with three equivalent O(3)Li3Fe2Co octahedra, corners with three equivalent O(2)Li3Fe3 octahedra,  an edgeedge with one O(3)Li3Fe2Co octahedra, edges with three equivalent O(2)Li3Fe3 octahedra, and edges with eight equivalent O(1)Li3Fe2Co octahedra. The corner-sharing octahedral tilt angles range from 0-6°.