CaFe2Sb2(PO4)6 crystallizes in the trigonal R-3 space group. Ca(1) is bonded in a distorted hexagonal planar geometry to six equivalent O(4) atoms. Fe(1) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. Sb(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form SbO6 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 Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 28-48°. There are four 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 Sb(1) and one P(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Fe(1), and one P(1) atom.
CaFe2Sb2(PO4)6 crystallizes in the trigonal R-3 space group. Ca(1) is bonded in a distorted hexagonal planar geometry to six equivalent O(4) atoms. All Ca(1)-O(4) bond lengths are 2.44 Å. Fe(1) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. All Fe(1)-O(3) bond lengths are 1.96 Å. All Fe(1)-O(4) bond lengths are 2.08 Å. Sb(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form SbO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. All Sb(1)-O(1) bond lengths are 1.99 Å. All Sb(1)-O(2) bond lengths are 1.98 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 Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 28-48°. The P(1)-O(1) bond length is 1.59 Å. The P(1)-O(2) bond length is 1.57 Å. The P(1)-O(3) bond length is 1.51 Å. The P(1)-O(4) bond length is 1.54 Å. There are four 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 Sb(1) and one P(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Fe(1), and one P(1) atom.