Nb3Fe(PO4)6 crystallizes in the trigonal R3 space group. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to three equivalent O(2) and three equivalent O(5) atoms to form NbO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. In the second Nb site, Nb(2) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form NbO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. In the third Nb site, Nb(3) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form NbO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. Fe(1) is bonded to three equivalent O(4) 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. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra, and  a cornercorner with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-30°. In the second P site, P(2) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra, and  a cornercorner with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 20-31°. There are eight inequivalent O sites. In the first O site, O(2) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(1) atom. In the second O site, O(3) is bonded in a bent 150 degrees geometry to one Nb(2) and one P(1) atom. In the third O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the fourth O site, O(5) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(2) atom. In the fifth O site, O(6) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the sixth O site, O(7) is bonded in a bent 150 degrees geometry to one Nb(3) and one P(2) atom. In the seventh O site, O(8) is bonded in a bent 150 degrees geometry to one Nb(3) and one P(1) atom. In the eighth O site, O(1) is bonded in a bent 150 degrees geometry to one Nb(2) and one P(2) atom.
Nb3Fe(PO4)6 crystallizes in the trigonal R3 space group. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to three equivalent O(2) and three equivalent O(5) atoms to form NbO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. All Nb(1)-O(2) bond lengths are 1.98 Å. All Nb(1)-O(5) bond lengths are 2.01 Å. In the second Nb site, Nb(2) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form NbO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. All Nb(2)-O(1) bond lengths are 2.00 Å. All Nb(2)-O(3) bond lengths are 1.98 Å. In the third Nb site, Nb(3) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form NbO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. All Nb(3)-O(7) bond lengths are 1.97 Å. All Nb(3)-O(8) bond lengths are 2.02 Å. Fe(1) is bonded to three equivalent O(4) 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(4) bond lengths are 2.01 Å. All Fe(1)-O(6) bond lengths are 1.99 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra, and  a cornercorner with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-30°. The P(1)-O(2) bond length is 1.56 Å. The P(1)-O(3) bond length is 1.56 Å. The P(1)-O(4) bond length is 1.50 Å. The P(1)-O(8) bond length is 1.55 Å. In the second P site, P(2) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra, and  a cornercorner with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 20-31°. The P(2)-O(1) bond length is 1.55 Å. The P(2)-O(5) bond length is 1.55 Å. The P(2)-O(6) bond length is 1.50 Å. The P(2)-O(7) bond length is 1.57 Å. There are eight inequivalent O sites. In the first O site, O(2) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(1) atom. In the second O site, O(3) is bonded in a bent 150 degrees geometry to one Nb(2) and one P(1) atom. In the third O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the fourth O site, O(5) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(2) atom. In the fifth O site, O(6) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the sixth O site, O(7) is bonded in a bent 150 degrees geometry to one Nb(3) and one P(2) atom. In the seventh O site, O(8) is bonded in a bent 150 degrees geometry to one Nb(3) and one P(1) atom. In the eighth O site, O(1) is bonded in a bent 150 degrees geometry to one Nb(2) and one P(2) atom.