SrCaFe(PO4)2 crystallizes in the triclinic P-1 space group. Sr(1) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(4), one O(8), two equivalent O(1), and two equivalent O(6) atoms. Ca(1) is bonded to one O(1), one O(2), one O(4), one O(7), and two equivalent O(5) atoms to form distorted CaO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 58-86°. Fe(1) is bonded to one O(3), one O(4), one O(5), one O(7), and two equivalent O(8) atoms to form distorted FeO6 octahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 58-86°. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, and  an edgeedge with one Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-62°. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with three equivalent Ca(1)O6 octahedra, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-56°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Sr(1), one Ca(1), and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(1), one Ca(1), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Sr(1), one Ca(1), one Fe(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Fe(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Sr(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Fe(1), and one P(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Sr(1), two equivalent Fe(1), and one P(2) atom.
SrCaFe(PO4)2 crystallizes in the triclinic P-1 space group. Sr(1) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(4), one O(8), two equivalent O(1), and two equivalent O(6) atoms. The Sr(1)-O(2) bond length is 2.59 Å. The Sr(1)-O(3) bond length is 2.60 Å. The Sr(1)-O(4) bond length is 2.88 Å. The Sr(1)-O(8) bond length is 3.00 Å. There is one shorter (2.63 Å) and one longer (2.85 Å) Sr(1)-O(1) bond length. There is one shorter (2.57 Å) and one longer (2.66 Å) Sr(1)-O(6) bond length. Ca(1) is bonded to one O(1), one O(2), one O(4), one O(7), and two equivalent O(5) atoms to form distorted CaO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 58-86°. The Ca(1)-O(1) bond length is 2.40 Å. The Ca(1)-O(2) bond length is 2.30 Å. The Ca(1)-O(4) bond length is 2.33 Å. The Ca(1)-O(7) bond length is 2.40 Å. There is one shorter (2.32 Å) and one longer (2.46 Å) Ca(1)-O(5) bond length. Fe(1) is bonded to one O(3), one O(4), one O(5), one O(7), and two equivalent O(8) atoms to form distorted FeO6 octahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 58-86°. The Fe(1)-O(3) bond length is 2.09 Å. The Fe(1)-O(4) bond length is 2.17 Å. The Fe(1)-O(5) bond length is 2.47 Å. The Fe(1)-O(7) bond length is 2.02 Å. There is one shorter (2.22 Å) and one longer (2.25 Å) Fe(1)-O(8) bond length. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, and  an edgeedge with one Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-62°. The P(1)-O(1) bond length is 1.56 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(7) bond length is 1.57 Å. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with three equivalent Ca(1)O6 octahedra, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-56°. The P(2)-O(4) bond length is 1.58 Å. The P(2)-O(5) bond length is 1.57 Å. The P(2)-O(6) bond length is 1.53 Å. The P(2)-O(8) bond length is 1.57 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Sr(1), one Ca(1), and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(1), one Ca(1), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Sr(1), one Ca(1), one Fe(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Fe(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Sr(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Fe(1), and one P(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Sr(1), two equivalent Fe(1), and one P(2) atom.