Fe9PO12 crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4), one O(5), and four equivalent O(3) atoms to form a mixture of distorted corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the second Fe site, Fe(2) is bonded to one O(5), one O(8), and four equivalent O(1) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with four equivalent Fe(7)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Fe(4)O6 octahedra. The corner-sharing octahedra are not tilted. In the third Fe site, Fe(3) is bonded to one O(4), one O(9), and four equivalent O(2) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(7)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with four equivalent Fe(5)O6 octahedra. The corner-sharing octahedra are not tilted. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(3), two equivalent O(5), and two equivalent O(7) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(5)O6 octahedra, corners with four equivalent Fe(4)O6 octahedra,  a cornercorner with one Fe(7)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(6)O6 octahedra, and edges with four equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-19°. In the fifth Fe site, Fe(5) is bonded to one O(2), one O(3), two equivalent O(4), and two equivalent O(6) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(4)O6 octahedra, corners with four equivalent Fe(5)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, edges with two equivalent Fe(6)O6 octahedra, and edges with four equivalent Fe(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-18°. In the sixth Fe site, Fe(6) is bonded to one O(6), one O(7), and four equivalent O(3) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles are 6°. In the seventh Fe site, Fe(7) is bonded to two equivalent O(1) and two equivalent O(9) atoms to form FeO4 tetrahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with four equivalent Fe(2)O6 octahedra, and corners with two equivalent Fe(7)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-60°. P(1) is bonded to two equivalent O(2) and two equivalent O(8) atoms to form PO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(5)O6 octahedra, corners with four equivalent Fe(3)O6 octahedra, and corners with two equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-63°. There are nine inequivalent O sites. In the first O site, O(1) is bonded to one Fe(4), one Fe(7), and two equivalent Fe(2) atoms to form distorted OFe4 trigonal pyramids that share  a cornercorner with one O(3)Fe6 octahedra, corners with two equivalent O(7)Fe5 square pyramids, corners with five equivalent O(1)Fe4 trigonal pyramids, edges with two equivalent O(5)Fe6 octahedra, and  an edgeedge with one O(1)Fe4 trigonal pyramid. The corner-sharing octahedral tilt angles are 5°. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Fe(5), two equivalent Fe(3), and one P(1) atom. In the third O site, O(3) is bonded to one Fe(4), one Fe(5), two equivalent Fe(1), and two equivalent Fe(6) atoms to form OFe6 octahedra that share corners with four equivalent O(3)Fe6 octahedra,  a cornercorner with one O(1)Fe4 trigonal pyramid, edges with two equivalent O(5)Fe6 octahedra, edges with four equivalent O(3)Fe6 octahedra, edges with two equivalent O(6)Fe5 square pyramids, and edges with two equivalent O(7)Fe5 square pyramids. The corner-sharing octahedral tilt angles range from 3-9°. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Fe(1), one Fe(3), and four equivalent Fe(5) atoms. In the fifth O site, O(5) is bonded to one Fe(1), one Fe(2), and four equivalent Fe(4) atoms to form OFe6 octahedra that share corners with four equivalent O(7)Fe5 square pyramids, edges with two equivalent O(5)Fe6 octahedra, edges with four equivalent O(3)Fe6 octahedra, edges with two equivalent O(7)Fe5 square pyramids, and edges with four equivalent O(1)Fe4 trigonal pyramids. In the sixth O site, O(6) is bonded to one Fe(6) and four equivalent Fe(5) atoms to form OFe5 square pyramids that share  a cornercorner with one O(7)Fe5 square pyramid, edges with four equivalent O(3)Fe6 octahedra, and edges with two equivalent O(6)Fe5 square pyramids. In the seventh O site, O(7) is bonded to one Fe(6) and four equivalent Fe(4) atoms to form OFe5 square pyramids that share corners with four equivalent O(5)Fe6 octahedra,  a cornercorner with one O(6)Fe5 square pyramid, corners with four equivalent O(1)Fe4 trigonal pyramids, edges with two equivalent O(5)Fe6 octahedra, edges with four equivalent O(3)Fe6 octahedra, and edges with two equivalent O(7)Fe5 square pyramids. The corner-sharing octahedral tilt angles are 11°. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent P(1) atoms. In the ninth O site, O(9) is bonded in a trigonal planar geometry to one Fe(3) and two equivalent Fe(7) atoms.
Fe9PO12 crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4), one O(5), and four equivalent O(3) atoms to form a mixture of distorted corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. The Fe(1)-O(4) bond length is 2.72 Å. The Fe(1)-O(5) bond length is 2.18 Å. All Fe(1)-O(3) bond lengths are 2.14 Å. In the second Fe site, Fe(2) is bonded to one O(5), one O(8), and four equivalent O(1) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with four equivalent Fe(7)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Fe(4)O6 octahedra. The corner-sharing octahedra are not tilted. The Fe(2)-O(5) bond length is 2.31 Å. The Fe(2)-O(8) bond length is 2.51 Å. All Fe(2)-O(1) bond lengths are 2.11 Å. In the third Fe site, Fe(3) is bonded to one O(4), one O(9), and four equivalent O(2) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(7)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with four equivalent Fe(5)O6 octahedra. The corner-sharing octahedra are not tilted. The Fe(3)-O(4) bond length is 2.08 Å. The Fe(3)-O(9) bond length is 1.99 Å. All Fe(3)-O(2) bond lengths are 2.31 Å. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(3), two equivalent O(5), and two equivalent O(7) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(5)O6 octahedra, corners with four equivalent Fe(4)O6 octahedra,  a cornercorner with one Fe(7)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(6)O6 octahedra, and edges with four equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-19°. The Fe(4)-O(1) bond length is 2.11 Å. The Fe(4)-O(3) bond length is 2.40 Å. Both Fe(4)-O(5) bond lengths are 2.19 Å. Both Fe(4)-O(7) bond lengths are 2.17 Å. In the fifth Fe site, Fe(5) is bonded to one O(2), one O(3), two equivalent O(4), and two equivalent O(6) atoms to form FeO6 octahedra that share  a cornercorner with one Fe(4)O6 octahedra, corners with four equivalent Fe(5)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, edges with two equivalent Fe(6)O6 octahedra, and edges with four equivalent Fe(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-18°. The Fe(5)-O(2) bond length is 2.28 Å. The Fe(5)-O(3) bond length is 2.22 Å. Both Fe(5)-O(4) bond lengths are 2.21 Å. Both Fe(5)-O(6) bond lengths are 2.15 Å. In the sixth Fe site, Fe(6) is bonded to one O(6), one O(7), and four equivalent O(3) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles are 6°. The Fe(6)-O(6) bond length is 2.04 Å. The Fe(6)-O(7) bond length is 1.99 Å. All Fe(6)-O(3) bond lengths are 2.19 Å. In the seventh Fe site, Fe(7) is bonded to two equivalent O(1) and two equivalent O(9) atoms to form FeO4 tetrahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with four equivalent Fe(2)O6 octahedra, and corners with two equivalent Fe(7)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-60°. Both Fe(7)-O(1) bond lengths are 1.89 Å. Both Fe(7)-O(9) bond lengths are 1.92 Å. P(1) is bonded to two equivalent O(2) and two equivalent O(8) atoms to form PO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(5)O6 octahedra, corners with four equivalent Fe(3)O6 octahedra, and corners with two equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-63°. Both P(1)-O(2) bond lengths are 1.56 Å. Both P(1)-O(8) bond lengths are 1.74 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded to one Fe(4), one Fe(7), and two equivalent Fe(2) atoms to form distorted OFe4 trigonal pyramids that share  a cornercorner with one O(3)Fe6 octahedra, corners with two equivalent O(7)Fe5 square pyramids, corners with five equivalent O(1)Fe4 trigonal pyramids, edges with two equivalent O(5)Fe6 octahedra, and  an edgeedge with one O(1)Fe4 trigonal pyramid. The corner-sharing octahedral tilt angles are 5°. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Fe(5), two equivalent Fe(3), and one P(1) atom. In the third O site, O(3) is bonded to one Fe(4), one Fe(5), two equivalent Fe(1), and two equivalent Fe(6) atoms to form OFe6 octahedra that share corners with four equivalent O(3)Fe6 octahedra,  a cornercorner with one O(1)Fe4 trigonal pyramid, edges with two equivalent O(5)Fe6 octahedra, edges with four equivalent O(3)Fe6 octahedra, edges with two equivalent O(6)Fe5 square pyramids, and edges with two equivalent O(7)Fe5 square pyramids. The corner-sharing octahedral tilt angles range from 3-9°. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Fe(1), one Fe(3), and four equivalent Fe(5) atoms. In the fifth O site, O(5) is bonded to one Fe(1), one Fe(2), and four equivalent Fe(4) atoms to form OFe6 octahedra that share corners with four equivalent O(7)Fe5 square pyramids, edges with two equivalent O(5)Fe6 octahedra, edges with four equivalent O(3)Fe6 octahedra, edges with two equivalent O(7)Fe5 square pyramids, and edges with four equivalent O(1)Fe4 trigonal pyramids. In the sixth O site, O(6) is bonded to one Fe(6) and four equivalent Fe(5) atoms to form OFe5 square pyramids that share  a cornercorner with one O(7)Fe5 square pyramid, edges with four equivalent O(3)Fe6 octahedra, and edges with two equivalent O(6)Fe5 square pyramids. In the seventh O site, O(7) is bonded to one Fe(6) and four equivalent Fe(4) atoms to form OFe5 square pyramids that share corners with four equivalent O(5)Fe6 octahedra,  a cornercorner with one O(6)Fe5 square pyramid, corners with four equivalent O(1)Fe4 trigonal pyramids, edges with two equivalent O(5)Fe6 octahedra, edges with four equivalent O(3)Fe6 octahedra, and edges with two equivalent O(7)Fe5 square pyramids. The corner-sharing octahedral tilt angles are 11°. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Fe(2) and two equivalent P(1) atoms. In the ninth O site, O(9) is bonded in a trigonal planar geometry to one Fe(3) and two equivalent Fe(7) atoms.