Li4Fe2SiO7 crystallizes in the triclinic P-1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form LiO6 octahedra that share  a cornercorner with one Li(1)O6 octahedra,  a cornercorner with one Si(1)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, corners with three equivalent Li(2)O5 square pyramids, edges with two equivalent Li(1)O6 octahedra, edges with two equivalent Si(1)O6 octahedra, edges with four equivalent Fe(1)O6 octahedra, and edges with three equivalent Li(2)O5 square pyramids. The corner-sharing octahedral tilt angles range from 0-22°. In the second Li site, Li(2) is bonded to one O(2), one O(3), one O(4), and two equivalent O(1) atoms to form distorted LiO5 square pyramids that share corners with three equivalent Li(1)O6 octahedra, corners with four equivalent Fe(1)O6 octahedra,  a cornercorner with one Li(2)O5 square pyramid, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Si(1)O6 octahedra, edges with three equivalent Li(1)O6 octahedra, and  an edgeedge with one Li(2)O5 square pyramid. The corner-sharing octahedral tilt angles range from 12-87°. Fe(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Si(1)O6 octahedra, corners with two equivalent Li(1)O6 octahedra, corners with four equivalent Li(2)O5 square pyramids, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Si(1)O6 octahedra, edges with four equivalent Li(1)O6 octahedra, and edges with two equivalent Li(2)O5 square pyramids. The corner-sharing octahedral tilt angles range from 0-22°. Si(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form SiO6 octahedra that share corners with two equivalent Li(1)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, edges with four equivalent Li(1)O6 octahedra, edges with four equivalent Fe(1)O6 octahedra, and edges with four equivalent Li(2)O5 square pyramids. The corner-sharing octahedral tilt angles range from 5-8°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Li(1), two equivalent Li(2), one Fe(1), and one Si(1) atom to form OLi4FeSi octahedra that share  a cornercorner with one O(2)Li4Fe2 octahedra,  a cornercorner with one O(1)Li4FeSi octahedra, corners with two equivalent O(3)Li3Fe2Si octahedra, corners with two equivalent O(4)Li2Fe2Si square pyramids, edges with two equivalent O(2)Li4Fe2 octahedra, edges with two equivalent O(1)Li4FeSi octahedra, edges with four equivalent O(3)Li3Fe2Si octahedra, and edges with three equivalent O(4)Li2Fe2Si square pyramids. The corner-sharing octahedral tilt angles range from 0-16°. In the second O site, O(2) is bonded to two equivalent Li(1), two equivalent Li(2), and two equivalent Fe(1) atoms to form OLi4Fe2 octahedra that share corners with two equivalent O(3)Li3Fe2Si octahedra, corners with two equivalent O(1)Li4FeSi octahedra, corners with four equivalent O(4)Li2Fe2Si square pyramids, edges with four equivalent O(3)Li3Fe2Si octahedra, edges with four equivalent O(1)Li4FeSi octahedra, and edges with two equivalent O(4)Li2Fe2Si square pyramids. The corner-sharing octahedral tilt angles range from 2-16°. In the third O site, O(3) is bonded to one Li(2), two equivalent Li(1), two equivalent Fe(1), and one Si(1) atom to form OLi3Fe2Si octahedra that share  a cornercorner with one O(3)Li3Fe2Si octahedra,  a cornercorner with one O(2)Li4Fe2 octahedra, corners with two equivalent O(1)Li4FeSi octahedra, corners with three equivalent O(4)Li2Fe2Si square pyramids, edges with two equivalent O(3)Li3Fe2Si octahedra, edges with two equivalent O(2)Li4Fe2 octahedra, edges with four equivalent O(1)Li4FeSi octahedra, and edges with three equivalent O(4)Li2Fe2Si square pyramids. The corner-sharing octahedral tilt angles range from 0-13°. In the fourth O site, O(4) is bonded to one Li(1), one Li(2), two equivalent Fe(1), and one Si(1) atom to form distorted OLi2Fe2Si square pyramids that share corners with two equivalent O(2)Li4Fe2 octahedra, corners with two equivalent O(1)Li4FeSi octahedra, corners with three equivalent O(3)Li3Fe2Si octahedra,  a cornercorner with one O(4)Li2Fe2Si square pyramid,  an edgeedge with one O(2)Li4Fe2 octahedra, edges with three equivalent O(3)Li3Fe2Si octahedra, edges with three equivalent O(1)Li4FeSi octahedra, and  an edgeedge with one O(4)Li2Fe2Si square pyramid. The corner-sharing octahedral tilt angles range from 4-88°.
Li4Fe2SiO7 crystallizes in the triclinic P-1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form LiO6 octahedra that share  a cornercorner with one Li(1)O6 octahedra,  a cornercorner with one Si(1)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, corners with three equivalent Li(2)O5 square pyramids, edges with two equivalent Li(1)O6 octahedra, edges with two equivalent Si(1)O6 octahedra, edges with four equivalent Fe(1)O6 octahedra, and edges with three equivalent Li(2)O5 square pyramids. The corner-sharing octahedral tilt angles range from 0-22°. The Li(1)-O(2) bond length is 2.10 Å. The Li(1)-O(4) bond length is 2.03 Å. There is one shorter (2.03 Å) and one longer (2.25 Å) Li(1)-O(1) bond length. There is one shorter (2.10 Å) and one longer (2.31 Å) Li(1)-O(3) bond length. In the second Li site, Li(2) is bonded to one O(2), one O(3), one O(4), and two equivalent O(1) atoms to form distorted LiO5 square pyramids that share corners with three equivalent Li(1)O6 octahedra, corners with four equivalent Fe(1)O6 octahedra,  a cornercorner with one Li(2)O5 square pyramid, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Si(1)O6 octahedra, edges with three equivalent Li(1)O6 octahedra, and  an edgeedge with one Li(2)O5 square pyramid. The corner-sharing octahedral tilt angles range from 12-87°. The Li(2)-O(2) bond length is 2.03 Å. The Li(2)-O(3) bond length is 2.08 Å. The Li(2)-O(4) bond length is 2.06 Å. There is one shorter (2.02 Å) and one longer (2.10 Å) Li(2)-O(1) bond length. Fe(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Si(1)O6 octahedra, corners with two equivalent Li(1)O6 octahedra, corners with four equivalent Li(2)O5 square pyramids, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Si(1)O6 octahedra, edges with four equivalent Li(1)O6 octahedra, and edges with two equivalent Li(2)O5 square pyramids. The corner-sharing octahedral tilt angles range from 0-22°. The Fe(1)-O(1) bond length is 2.00 Å. The Fe(1)-O(2) bond length is 1.97 Å. There is one shorter (2.07 Å) and one longer (2.08 Å) Fe(1)-O(3) bond length. There is one shorter (2.08 Å) and one longer (2.10 Å) Fe(1)-O(4) bond length. Si(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form SiO6 octahedra that share corners with two equivalent Li(1)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, edges with four equivalent Li(1)O6 octahedra, edges with four equivalent Fe(1)O6 octahedra, and edges with four equivalent Li(2)O5 square pyramids. The corner-sharing octahedral tilt angles range from 5-8°. Both Si(1)-O(1) bond lengths are 1.81 Å. Both Si(1)-O(3) bond lengths are 1.89 Å. Both Si(1)-O(4) bond lengths are 1.81 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Li(1), two equivalent Li(2), one Fe(1), and one Si(1) atom to form OLi4FeSi octahedra that share  a cornercorner with one O(2)Li4Fe2 octahedra,  a cornercorner with one O(1)Li4FeSi octahedra, corners with two equivalent O(3)Li3Fe2Si octahedra, corners with two equivalent O(4)Li2Fe2Si square pyramids, edges with two equivalent O(2)Li4Fe2 octahedra, edges with two equivalent O(1)Li4FeSi octahedra, edges with four equivalent O(3)Li3Fe2Si octahedra, and edges with three equivalent O(4)Li2Fe2Si square pyramids. The corner-sharing octahedral tilt angles range from 0-16°. In the second O site, O(2) is bonded to two equivalent Li(1), two equivalent Li(2), and two equivalent Fe(1) atoms to form OLi4Fe2 octahedra that share corners with two equivalent O(3)Li3Fe2Si octahedra, corners with two equivalent O(1)Li4FeSi octahedra, corners with four equivalent O(4)Li2Fe2Si square pyramids, edges with four equivalent O(3)Li3Fe2Si octahedra, edges with four equivalent O(1)Li4FeSi octahedra, and edges with two equivalent O(4)Li2Fe2Si square pyramids. The corner-sharing octahedral tilt angles range from 2-16°. In the third O site, O(3) is bonded to one Li(2), two equivalent Li(1), two equivalent Fe(1), and one Si(1) atom to form OLi3Fe2Si octahedra that share  a cornercorner with one O(3)Li3Fe2Si octahedra,  a cornercorner with one O(2)Li4Fe2 octahedra, corners with two equivalent O(1)Li4FeSi octahedra, corners with three equivalent O(4)Li2Fe2Si square pyramids, edges with two equivalent O(3)Li3Fe2Si octahedra, edges with two equivalent O(2)Li4Fe2 octahedra, edges with four equivalent O(1)Li4FeSi octahedra, and edges with three equivalent O(4)Li2Fe2Si square pyramids. The corner-sharing octahedral tilt angles range from 0-13°. In the fourth O site, O(4) is bonded to one Li(1), one Li(2), two equivalent Fe(1), and one Si(1) atom to form distorted OLi2Fe2Si square pyramids that share corners with two equivalent O(2)Li4Fe2 octahedra, corners with two equivalent O(1)Li4FeSi octahedra, corners with three equivalent O(3)Li3Fe2Si octahedra,  a cornercorner with one O(4)Li2Fe2Si square pyramid,  an edgeedge with one O(2)Li4Fe2 octahedra, edges with three equivalent O(3)Li3Fe2Si octahedra, edges with three equivalent O(1)Li4FeSi octahedra, and  an edgeedge with one O(4)Li2Fe2Si square pyramid. The corner-sharing octahedral tilt angles range from 4-88°.