LiFeSiO4 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 5-coordinate geometry to one O(2), one O(5), one O(6), and two equivalent O(1) atoms. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to one O(3), one O(4), and two equivalent O(8) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(3), and one O(7) atom to form FeO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. In the second Fe site, Fe(2) is bonded to one O(4), one O(6), one O(8), and two equivalent O(5) atoms to form distorted FeO5 trigonal bipyramids that share corners with two equivalent Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, and corners with two equivalent Fe(2)O5 trigonal bipyramids. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with three equivalent Fe(2)O5 trigonal bipyramids. In the second Si site, Si(2) is bonded to one O(2), one O(4), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with two equivalent Fe(2)O5 trigonal bipyramids. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Li(1), one Fe(1), and one Si(1) atom to form distorted corner-sharing OLi2FeSi tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one Si(2) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Li(2), one Fe(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Li(2), one Fe(2), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Li(1), two equivalent Fe(2), and one Si(1) atom. In the sixth O site, O(6) is bonded in a trigonal non-coplanar geometry to one Li(1), one Fe(2), and one Si(1) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Fe(1) and one Si(2) atom. In the eighth O site, O(8) is bonded to two equivalent Li(2), one Fe(2), and one Si(2) atom to form distorted corner-sharing OLi2FeSi tetrahedra.
LiFeSiO4 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 5-coordinate geometry to one O(2), one O(5), one O(6), and two equivalent O(1) atoms. The Li(1)-O(2) bond length is 1.93 Å. The Li(1)-O(5) bond length is 2.41 Å. The Li(1)-O(6) bond length is 2.03 Å. There is one shorter (2.14 Å) and one longer (2.23 Å) Li(1)-O(1) bond length. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to one O(3), one O(4), and two equivalent O(8) atoms. The Li(2)-O(3) bond length is 1.93 Å. The Li(2)-O(4) bond length is 1.99 Å. There is one shorter (2.03 Å) and one longer (2.31 Å) Li(2)-O(8) bond length. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(3), and one O(7) atom to form FeO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. The Fe(1)-O(1) bond length is 1.93 Å. The Fe(1)-O(2) bond length is 1.91 Å. The Fe(1)-O(3) bond length is 1.92 Å. The Fe(1)-O(7) bond length is 1.84 Å. In the second Fe site, Fe(2) is bonded to one O(4), one O(6), one O(8), and two equivalent O(5) atoms to form distorted FeO5 trigonal bipyramids that share corners with two equivalent Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, and corners with two equivalent Fe(2)O5 trigonal bipyramids. The Fe(2)-O(4) bond length is 1.93 Å. The Fe(2)-O(6) bond length is 1.91 Å. The Fe(2)-O(8) bond length is 1.99 Å. There is one shorter (1.98 Å) and one longer (2.49 Å) Fe(2)-O(5) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with three equivalent Fe(2)O5 trigonal bipyramids. The Si(1)-O(1) bond length is 1.66 Å. The Si(1)-O(3) bond length is 1.64 Å. The Si(1)-O(5) bond length is 1.67 Å. The Si(1)-O(6) bond length is 1.64 Å. In the second Si site, Si(2) is bonded to one O(2), one O(4), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O4 tetrahedra and corners with two equivalent Fe(2)O5 trigonal bipyramids. The Si(2)-O(2) bond length is 1.64 Å. The Si(2)-O(4) bond length is 1.64 Å. The Si(2)-O(7) bond length is 1.63 Å. The Si(2)-O(8) bond length is 1.66 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Li(1), one Fe(1), and one Si(1) atom to form distorted corner-sharing OLi2FeSi tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one Si(2) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Li(2), one Fe(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Li(2), one Fe(2), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Li(1), two equivalent Fe(2), and one Si(1) atom. In the sixth O site, O(6) is bonded in a trigonal non-coplanar geometry to one Li(1), one Fe(2), and one Si(1) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Fe(1) and one Si(2) atom. In the eighth O site, O(8) is bonded to two equivalent Li(2), one Fe(2), and one Si(2) atom to form distorted corner-sharing OLi2FeSi tetrahedra.