Li2FePO5 crystallizes in the monoclinic Pc space group. There are four inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(4), one O(6), one O(8), and one O(9) atom to form LiO4 tetrahedra that share  a cornercorner with one Fe(2)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with two equivalent Li(3)O4 tetrahedra, corners with two equivalent Li(4)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, and corners with two equivalent P(1)O4 tetrahedra. In the second Li site, Li(2) is bonded to one O(10), one O(3), one O(5), and one O(7) atom to form LiO4 tetrahedra that share  a cornercorner with one Fe(1)O4 tetrahedra,  a cornercorner with one P(1)O4 tetrahedra, corners with two equivalent Li(3)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. In the third Li site, Li(3) is bonded to one O(5), one O(7), one O(8), and one O(9) atom to form distorted LiO4 tetrahedra that share  a cornercorner with one Fe(1)O4 tetrahedra, corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. In the fourth Li site, Li(4) is bonded to one O(1), one O(2), one O(4), and one O(6) atom to form LiO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, and corners with two equivalent P(1)O4 tetrahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(3), one O(4), and one O(9) atom to form FeO4 tetrahedra that share  a cornercorner with one Li(2)O4 tetrahedra,  a cornercorner with one Li(3)O4 tetrahedra, corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(4)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, and corners with two equivalent P(1)O4 tetrahedra. In the second Fe site, Fe(2) is bonded to one O(10), one O(2), one O(3), and one O(4) atom to form FeO4 tetrahedra that share  a cornercorner with one Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Li(4)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(6), one O(7), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Li(2)O4 tetrahedra, corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(3)O4 tetrahedra, corners with two equivalent Li(4)O4 tetrahedra, and corners with two equivalent Fe(1)O4 tetrahedra. In the second P site, P(2) is bonded to one O(10), one O(2), one O(5), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Li(1)O4 tetrahedra,  a cornercorner with one Li(4)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Li(3)O4 tetrahedra, and corners with two equivalent Fe(2)O4 tetrahedra. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Li(4), one Fe(1), and one P(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Li(4), one Fe(2), and one P(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 Fe(2) atom. In the fourth O site, O(4) is bonded to one Li(1), one Li(4), one Fe(1), and one Fe(2) atom to form corner-sharing OLi2Fe2 tetrahedra. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Li(2), one Li(3), and one P(2) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Li(1), one Li(4), and one P(1) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Li(2), one Li(3), and one P(1) atom. In the eighth O site, O(8) is bonded in a trigonal non-coplanar geometry to one Li(1), one Li(3), and one P(2) atom. In the ninth O site, O(9) is bonded to one Li(1), one Li(3), one Fe(1), and one P(1) atom to form corner-sharing OLi2FeP tetrahedra. In the tenth O site, O(10) is bonded in a trigonal non-coplanar geometry to one Li(2), one Fe(2), and one P(2) atom.
Li2FePO5 crystallizes in the monoclinic Pc space group. There are four inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(4), one O(6), one O(8), and one O(9) atom to form LiO4 tetrahedra that share  a cornercorner with one Fe(2)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with two equivalent Li(3)O4 tetrahedra, corners with two equivalent Li(4)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, and corners with two equivalent P(1)O4 tetrahedra. The Li(1)-O(4) bond length is 2.06 Å. The Li(1)-O(6) bond length is 2.02 Å. The Li(1)-O(8) bond length is 1.96 Å. The Li(1)-O(9) bond length is 2.18 Å. In the second Li site, Li(2) is bonded to one O(10), one O(3), one O(5), and one O(7) atom to form LiO4 tetrahedra that share  a cornercorner with one Fe(1)O4 tetrahedra,  a cornercorner with one P(1)O4 tetrahedra, corners with two equivalent Li(3)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. The Li(2)-O(10) bond length is 2.03 Å. The Li(2)-O(3) bond length is 1.98 Å. The Li(2)-O(5) bond length is 1.97 Å. The Li(2)-O(7) bond length is 1.92 Å. In the third Li site, Li(3) is bonded to one O(5), one O(7), one O(8), and one O(9) atom to form distorted LiO4 tetrahedra that share  a cornercorner with one Fe(1)O4 tetrahedra, corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. The Li(3)-O(5) bond length is 1.92 Å. The Li(3)-O(7) bond length is 2.00 Å. The Li(3)-O(8) bond length is 1.94 Å. The Li(3)-O(9) bond length is 2.23 Å. In the fourth Li site, Li(4) is bonded to one O(1), one O(2), one O(4), and one O(6) atom to form LiO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, and corners with two equivalent P(1)O4 tetrahedra. The Li(4)-O(1) bond length is 2.05 Å. The Li(4)-O(2) bond length is 2.13 Å. The Li(4)-O(4) bond length is 2.00 Å. The Li(4)-O(6) bond length is 1.93 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(3), one O(4), and one O(9) atom to form FeO4 tetrahedra that share  a cornercorner with one Li(2)O4 tetrahedra,  a cornercorner with one Li(3)O4 tetrahedra, corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(4)O4 tetrahedra, corners with two equivalent Fe(2)O4 tetrahedra, and corners with two equivalent P(1)O4 tetrahedra. The Fe(1)-O(1) bond length is 1.95 Å. The Fe(1)-O(3) bond length is 1.85 Å. The Fe(1)-O(4) bond length is 1.90 Å. The Fe(1)-O(9) bond length is 1.97 Å. In the second Fe site, Fe(2) is bonded to one O(10), one O(2), one O(3), and one O(4) atom to form FeO4 tetrahedra that share  a cornercorner with one Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Li(4)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. The Fe(2)-O(10) bond length is 1.91 Å. The Fe(2)-O(2) bond length is 1.93 Å. The Fe(2)-O(3) bond length is 1.86 Å. The Fe(2)-O(4) bond length is 1.92 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(6), one O(7), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Li(2)O4 tetrahedra, corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(3)O4 tetrahedra, corners with two equivalent Li(4)O4 tetrahedra, and corners with two equivalent Fe(1)O4 tetrahedra. The P(1)-O(1) bond length is 1.60 Å. The P(1)-O(6) bond length is 1.52 Å. The P(1)-O(7) bond length is 1.53 Å. The P(1)-O(9) bond length is 1.60 Å. In the second P site, P(2) is bonded to one O(10), one O(2), one O(5), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Li(1)O4 tetrahedra,  a cornercorner with one Li(4)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Li(3)O4 tetrahedra, and corners with two equivalent Fe(2)O4 tetrahedra. The P(2)-O(10) bond length is 1.58 Å. The P(2)-O(2) bond length is 1.60 Å. The P(2)-O(5) bond length is 1.53 Å. The P(2)-O(8) bond length is 1.53 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Li(4), one Fe(1), and one P(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Li(4), one Fe(2), and one P(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 Fe(2) atom. In the fourth O site, O(4) is bonded to one Li(1), one Li(4), one Fe(1), and one Fe(2) atom to form corner-sharing OLi2Fe2 tetrahedra. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Li(2), one Li(3), and one P(2) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Li(1), one Li(4), and one P(1) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Li(2), one Li(3), and one P(1) atom. In the eighth O site, O(8) is bonded in a trigonal non-coplanar geometry to one Li(1), one Li(3), and one P(2) atom. In the ninth O site, O(9) is bonded to one Li(1), one Li(3), one Fe(1), and one P(1) atom to form corner-sharing OLi2FeP tetrahedra. In the tenth O site, O(10) is bonded in a trigonal non-coplanar geometry to one Li(2), one Fe(2), and one P(2) atom.