Fe2(PO4)3 crystallizes in the trigonal R-3 space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. In the second Fe site, Fe(2) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-39°. There are four inequivalent O sites. In the first O site, O(3) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(1) atom. In the second O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the third O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the fourth O site, O(2) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(1) atom.
Fe2(PO4)3 crystallizes in the trigonal R-3 space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. All Fe(1)-O(1) bond lengths are 2.01 Å. All Fe(1)-O(4) bond lengths are 1.98 Å. In the second Fe site, Fe(2) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. All Fe(2)-O(2) bond lengths are 1.99 Å. All Fe(2)-O(3) bond lengths are 2.00 Å. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-39°. The P(1)-O(1) bond length is 1.55 Å. The P(1)-O(2) bond length is 1.54 Å. The P(1)-O(3) bond length is 1.54 Å. The P(1)-O(4) bond length is 1.54 Å. There are four inequivalent O sites. In the first O site, O(3) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(1) atom. In the second O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the third O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the fourth O site, O(2) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(1) atom.