Li3Fe2(SiO4)2 crystallizes in the monoclinic Pc space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form LiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Li(3)O4 trigonal pyramids. In the second Li site, Li(2) is bonded to one O(4), one O(6), one O(7), and one O(8) atom to form LiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Li(3)O4 trigonal pyramid. In the third Li site, Li(3) is bonded to one O(2), one O(5), one O(6), and one O(8) atom to form distorted LiO4 trigonal pyramids that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Li(2)O4 tetrahedra, and  an edgeedge with one Fe(2)O4 tetrahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(4), and one O(6) atom to form FeO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Li(3)O4 trigonal pyramids. In the second Fe site, Fe(2) is bonded to one O(3), one O(5), one O(7), and one O(8) atom to form FeO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Li(3)O4 trigonal pyramid. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(4), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, and corners with two equivalent Li(3)O4 trigonal pyramids. In the second Si site, Si(2) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, and corners with two equivalent Li(3)O4 trigonal pyramids. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one Si(2) atom. In the second O site, O(2) is bonded to one Li(1), one Li(3), one Fe(1), and one Si(1) atom to form corner-sharing OLi2FeSi tetrahedra. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to one Li(1), one Fe(2), and one Si(1) atom. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Li(2), one Fe(1), and one Si(1) atom. In the fifth O site, O(5) is bonded to one Li(1), one Li(3), one Fe(2), and one Si(2) atom to form a mixture of edge and corner-sharing OLi2FeSi tetrahedra. In the sixth O site, O(6) is bonded to one Li(2), one Li(3), one Fe(1), and one Si(2) atom to form a mixture of edge and corner-sharing OLi2FeSi tetrahedra. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Li(2), one Fe(2), and one Si(2) atom. In the eighth O site, O(8) is bonded to one Li(2), one Li(3), one Fe(2), and one Si(1) atom to form a mixture of distorted edge and corner-sharing OLi2FeSi trigonal pyramids.
Li3Fe2(SiO4)2 crystallizes in the monoclinic Pc space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form LiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Li(3)O4 trigonal pyramids. The Li(1)-O(1) bond length is 1.90 Å. The Li(1)-O(2) bond length is 2.01 Å. The Li(1)-O(3) bond length is 2.02 Å. The Li(1)-O(5) bond length is 2.10 Å. In the second Li site, Li(2) is bonded to one O(4), one O(6), one O(7), and one O(8) atom to form LiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Li(3)O4 trigonal pyramid. The Li(2)-O(4) bond length is 1.95 Å. The Li(2)-O(6) bond length is 2.03 Å. The Li(2)-O(7) bond length is 1.98 Å. The Li(2)-O(8) bond length is 2.16 Å. In the third Li site, Li(3) is bonded to one O(2), one O(5), one O(6), and one O(8) atom to form distorted LiO4 trigonal pyramids that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Li(2)O4 tetrahedra, and  an edgeedge with one Fe(2)O4 tetrahedra. The Li(3)-O(2) bond length is 1.94 Å. The Li(3)-O(5) bond length is 2.17 Å. The Li(3)-O(6) bond length is 2.01 Å. The Li(3)-O(8) bond length is 2.25 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(4), and one O(6) atom to form FeO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Li(3)O4 trigonal pyramids. The Fe(1)-O(1) bond length is 1.97 Å. The Fe(1)-O(2) bond length is 2.10 Å. The Fe(1)-O(4) bond length is 2.02 Å. The Fe(1)-O(6) bond length is 2.07 Å. In the second Fe site, Fe(2) is bonded to one O(3), one O(5), one O(7), and one O(8) atom to form FeO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Li(3)O4 trigonal pyramid. The Fe(2)-O(3) bond length is 1.88 Å. The Fe(2)-O(5) bond length is 1.93 Å. The Fe(2)-O(7) bond length is 1.87 Å. The Fe(2)-O(8) bond length is 1.94 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(4), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, and corners with two equivalent Li(3)O4 trigonal pyramids. The Si(1)-O(2) bond length is 1.65 Å. The Si(1)-O(3) bond length is 1.66 Å. The Si(1)-O(4) bond length is 1.62 Å. The Si(1)-O(8) bond length is 1.68 Å. In the second Si site, Si(2) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, and corners with two equivalent Li(3)O4 trigonal pyramids. The Si(2)-O(1) bond length is 1.62 Å. The Si(2)-O(5) bond length is 1.69 Å. The Si(2)-O(6) bond length is 1.65 Å. The Si(2)-O(7) bond length is 1.66 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one Si(2) atom. In the second O site, O(2) is bonded to one Li(1), one Li(3), one Fe(1), and one Si(1) atom to form corner-sharing OLi2FeSi tetrahedra. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to one Li(1), one Fe(2), and one Si(1) atom. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Li(2), one Fe(1), and one Si(1) atom. In the fifth O site, O(5) is bonded to one Li(1), one Li(3), one Fe(2), and one Si(2) atom to form a mixture of edge and corner-sharing OLi2FeSi tetrahedra. In the sixth O site, O(6) is bonded to one Li(2), one Li(3), one Fe(1), and one Si(2) atom to form a mixture of edge and corner-sharing OLi2FeSi tetrahedra. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Li(2), one Fe(2), and one Si(2) atom. In the eighth O site, O(8) is bonded to one Li(2), one Li(3), one Fe(2), and one Si(1) atom to form a mixture of distorted edge and corner-sharing OLi2FeSi trigonal pyramids.