Sr2Fe3Sb(PO4)6 crystallizes in the trigonal R3 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a distorted hexagonal planar geometry to three equivalent O(5) and three equivalent O(7) atoms. In the second Sr site, Sr(2) is bonded in a distorted hexagonal planar geometry to three equivalent O(6) and three equivalent O(8) atoms. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent O(2) and three equivalent O(6) atoms to form FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. In the second Fe site, Fe(2) is bonded to three equivalent O(3) and three equivalent O(7) atoms to form FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. In the third Fe site, Fe(3) is bonded to three equivalent O(4) and three equivalent O(8) atoms to form FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. Sb(1) is bonded to three equivalent O(1) and three equivalent O(5) atoms to form SbO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three 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(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, and  a cornercorner with one Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 29-37°. In the second P site, P(2) is bonded to one O(2), one O(3), one O(5), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, and  a cornercorner with one Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 31-35°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Sb(1) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Sr(1), one Sb(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Sr(2), one Fe(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(2), and one P(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Sr(2), one Fe(3), and one P(2) atom.
Sr2Fe3Sb(PO4)6 crystallizes in the trigonal R3 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a distorted hexagonal planar geometry to three equivalent O(5) and three equivalent O(7) atoms. All Sr(1)-O(5) bond lengths are 2.67 Å. All Sr(1)-O(7) bond lengths are 2.54 Å. In the second Sr site, Sr(2) is bonded in a distorted hexagonal planar geometry to three equivalent O(6) and three equivalent O(8) atoms. All Sr(2)-O(6) bond lengths are 2.59 Å. All Sr(2)-O(8) bond lengths are 2.60 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent O(2) and three equivalent O(6) atoms to form FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. All Fe(1)-O(2) bond lengths are 1.99 Å. All Fe(1)-O(6) bond lengths are 2.07 Å. In the second Fe site, Fe(2) is bonded to three equivalent O(3) and three equivalent O(7) atoms to form FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. All Fe(2)-O(3) bond lengths are 1.96 Å. All Fe(2)-O(7) bond lengths are 2.06 Å. In the third Fe site, Fe(3) is bonded to three equivalent O(4) and three equivalent O(8) atoms to form FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. All Fe(3)-O(4) bond lengths are 1.97 Å. All Fe(3)-O(8) bond lengths are 2.05 Å. Sb(1) is bonded to three equivalent O(1) and three equivalent O(5) atoms to form SbO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. All Sb(1)-O(1) bond lengths are 1.97 Å. All Sb(1)-O(5) bond lengths are 2.02 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, and  a cornercorner with one Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 29-37°. The P(1)-O(1) bond length is 1.60 Å. The P(1)-O(4) bond length is 1.52 Å. The P(1)-O(6) bond length is 1.54 Å. The P(1)-O(7) bond length is 1.54 Å. In the second P site, P(2) is bonded to one O(2), one O(3), one O(5), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, and  a cornercorner with one Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 31-35°. The P(2)-O(2) bond length is 1.53 Å. The P(2)-O(3) bond length is 1.52 Å. The P(2)-O(5) bond length is 1.61 Å. The P(2)-O(8) bond length is 1.53 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Sb(1) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Sr(1), one Sb(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Sr(2), one Fe(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(2), and one P(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Sr(2), one Fe(3), and one P(2) atom.