FePO4 crystallizes in the triclinic P1 space group. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(10), one O(13), one O(14), one O(15), one O(3), and one O(4) atom to form FeO6 octahedra that share corners with four equivalent Fe(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and  an edgeedge with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. In the second Fe site, Fe(2) is bonded to one O(1), one O(10), one O(15), one O(2), one O(3), and one O(4) atom to form FeO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, and  an edgeedge with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. In the third Fe site, Fe(3) is bonded to one O(12), one O(16), one O(6), one O(7), one O(8), and one O(9) atom to form distorted FeO6 octahedra that share corners with four equivalent Fe(4)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-49°. In the fourth Fe site, Fe(4) is bonded to one O(11), one O(16), one O(5), one O(7), one O(8), and one O(9) atom to form distorted FeO6 octahedra that share corners with four equivalent Fe(3)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-49°. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(13), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, and  an edgeedge with one Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-56°. In the second P site, P(2) is bonded to one O(1), one O(11), one O(16), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(4)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and  an edgeedge with one Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-55°. In the third P site, P(3) is bonded to one O(10), one O(12), one O(14), and one O(15) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-57°. In the fourth P site, P(4) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(4)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, and  an edgeedge with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-57°. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(2) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one P(4) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(2), and one P(4) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(2), and one P(4) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Fe(4) and one P(4) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Fe(3) and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Fe(3), one Fe(4), and one P(1) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Fe(3), one Fe(4), and one P(1) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Fe(3), one Fe(4), and one P(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(2), and one P(3) atom. In the eleventh O site, O(11) is bonded in a bent 120 degrees geometry to one Fe(4) and one P(2) atom. In the twelfth O site, O(12) is bonded in a distorted bent 150 degrees geometry to one Fe(3) and one P(3) atom. In the thirteenth O site, O(13) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one P(3) atom. In the fifteenth O site, O(15) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(2), and one P(3) atom. In the sixteenth O site, O(16) is bonded in a 3-coordinate geometry to one Fe(3), one Fe(4), and one P(2) atom.
FePO4 crystallizes in the triclinic P1 space group. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(10), one O(13), one O(14), one O(15), one O(3), and one O(4) atom to form FeO6 octahedra that share corners with four equivalent Fe(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and  an edgeedge with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. The Fe(1)-O(10) bond length is 2.15 Å. The Fe(1)-O(13) bond length is 1.95 Å. The Fe(1)-O(14) bond length is 1.94 Å. The Fe(1)-O(15) bond length is 2.15 Å. The Fe(1)-O(3) bond length is 2.07 Å. The Fe(1)-O(4) bond length is 2.07 Å. In the second Fe site, Fe(2) is bonded to one O(1), one O(10), one O(15), one O(2), one O(3), and one O(4) atom to form FeO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, and  an edgeedge with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. The Fe(2)-O(1) bond length is 1.94 Å. The Fe(2)-O(10) bond length is 2.07 Å. The Fe(2)-O(15) bond length is 2.07 Å. The Fe(2)-O(2) bond length is 1.94 Å. The Fe(2)-O(3) bond length is 2.15 Å. The Fe(2)-O(4) bond length is 2.15 Å. In the third Fe site, Fe(3) is bonded to one O(12), one O(16), one O(6), one O(7), one O(8), and one O(9) atom to form distorted FeO6 octahedra that share corners with four equivalent Fe(4)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-49°. The Fe(3)-O(12) bond length is 1.92 Å. The Fe(3)-O(16) bond length is 1.99 Å. The Fe(3)-O(6) bond length is 1.90 Å. The Fe(3)-O(7) bond length is 2.15 Å. The Fe(3)-O(8) bond length is 2.18 Å. The Fe(3)-O(9) bond length is 2.00 Å. In the fourth Fe site, Fe(4) is bonded to one O(11), one O(16), one O(5), one O(7), one O(8), and one O(9) atom to form distorted FeO6 octahedra that share corners with four equivalent Fe(3)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-49°. The Fe(4)-O(11) bond length is 1.90 Å. The Fe(4)-O(16) bond length is 2.30 Å. The Fe(4)-O(5) bond length is 1.93 Å. The Fe(4)-O(7) bond length is 2.03 Å. The Fe(4)-O(8) bond length is 1.97 Å. The Fe(4)-O(9) bond length is 2.28 Å. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(13), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, and  an edgeedge with one Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-56°. The P(1)-O(13) bond length is 1.53 Å. The P(1)-O(6) bond length is 1.53 Å. The P(1)-O(7) bond length is 1.58 Å. The P(1)-O(8) bond length is 1.59 Å. In the second P site, P(2) is bonded to one O(1), one O(11), one O(16), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(4)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and  an edgeedge with one Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-55°. The P(2)-O(1) bond length is 1.53 Å. The P(2)-O(11) bond length is 1.55 Å. The P(2)-O(16) bond length is 1.57 Å. The P(2)-O(9) bond length is 1.57 Å. In the third P site, P(3) is bonded to one O(10), one O(12), one O(14), and one O(15) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-57°. The P(3)-O(10) bond length is 1.58 Å. The P(3)-O(12) bond length is 1.53 Å. The P(3)-O(14) bond length is 1.52 Å. The P(3)-O(15) bond length is 1.58 Å. In the fourth P site, P(4) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(4)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, and  an edgeedge with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-57°. The P(4)-O(2) bond length is 1.52 Å. The P(4)-O(3) bond length is 1.58 Å. The P(4)-O(4) bond length is 1.58 Å. The P(4)-O(5) bond length is 1.53 Å. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(2) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Fe(2) and one P(4) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(2), and one P(4) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(2), and one P(4) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Fe(4) and one P(4) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Fe(3) and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Fe(3), one Fe(4), and one P(1) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Fe(3), one Fe(4), and one P(1) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Fe(3), one Fe(4), and one P(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(2), and one P(3) atom. In the eleventh O site, O(11) is bonded in a bent 120 degrees geometry to one Fe(4) and one P(2) atom. In the twelfth O site, O(12) is bonded in a distorted bent 150 degrees geometry to one Fe(3) and one P(3) atom. In the thirteenth O site, O(13) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one P(3) atom. In the fifteenth O site, O(15) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(2), and one P(3) atom. In the sixteenth O site, O(16) is bonded in a 3-coordinate geometry to one Fe(3), one Fe(4), and one P(2) atom.