SrNi2(PO4)2 crystallizes in the triclinic P-1 space group. Sr(1) is bonded in a 8-coordinate geometry to one O(3), one O(4), one O(5), one O(8), two equivalent O(1), and two equivalent O(2) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(1), one O(3), one O(5), one O(6), and one O(7) atom to form distorted NiO5 square pyramids that share corners with three equivalent Ni(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 58-73°. In the second Ni site, Ni(2) is bonded to one O(4), one O(5), one O(6), one O(7), and two equivalent O(8) atoms to form NiO6 octahedra that share corners with three equivalent Ni(1)O5 square pyramids, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra,  an edgeedge with one Ni(2)O6 octahedra, and  an edgeedge with one 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(3), one O(4), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Ni(2)O6 octahedra,  a cornercorner with one Ni(1)O5 square pyramid, and  an edgeedge with one Ni(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 51-58°. In the second P site, P(2) is bonded to one O(2), one O(5), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Ni(2)O6 octahedra, corners with two equivalent Ni(1)O5 square pyramids, and  an edgeedge with one Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-57°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), one Ni(1), and one P(1) atom to form distorted edge-sharing OSr2NiP trigonal pyramids. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent Sr(1) and one P(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sr(1), one Ni(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Sr(1), one Ni(2), and one P(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Sr(1), one Ni(1), one Ni(2), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ni(1), one Ni(2), and one P(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Sr(1), two equivalent Ni(2), and one P(2) atom.
SrNi2(PO4)2 crystallizes in the triclinic P-1 space group. Sr(1) is bonded in a 8-coordinate geometry to one O(3), one O(4), one O(5), one O(8), two equivalent O(1), and two equivalent O(2) atoms. The Sr(1)-O(3) bond length is 2.66 Å. The Sr(1)-O(4) bond length is 2.58 Å. The Sr(1)-O(5) bond length is 2.71 Å. The Sr(1)-O(8) bond length is 2.93 Å. There is one shorter (2.55 Å) and one longer (2.72 Å) Sr(1)-O(1) bond length. There is one shorter (2.53 Å) and one longer (2.69 Å) Sr(1)-O(2) bond length. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(1), one O(3), one O(5), one O(6), and one O(7) atom to form distorted NiO5 square pyramids that share corners with three equivalent Ni(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 58-73°. The Ni(1)-O(1) bond length is 2.25 Å. The Ni(1)-O(3) bond length is 2.04 Å. The Ni(1)-O(5) bond length is 2.04 Å. The Ni(1)-O(6) bond length is 2.03 Å. The Ni(1)-O(7) bond length is 2.03 Å. In the second Ni site, Ni(2) is bonded to one O(4), one O(5), one O(6), one O(7), and two equivalent O(8) atoms to form NiO6 octahedra that share corners with three equivalent Ni(1)O5 square pyramids, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra,  an edgeedge with one Ni(2)O6 octahedra, and  an edgeedge with one P(2)O4 tetrahedra. The Ni(2)-O(4) bond length is 2.03 Å. The Ni(2)-O(5) bond length is 2.12 Å. The Ni(2)-O(6) bond length is 1.98 Å. The Ni(2)-O(7) bond length is 2.17 Å. There is one shorter (2.11 Å) and one longer (2.13 Å) Ni(2)-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(3), one O(4), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Ni(2)O6 octahedra,  a cornercorner with one Ni(1)O5 square pyramid, and  an edgeedge with one Ni(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 51-58°. The P(1)-O(1) bond length is 1.57 Å. The P(1)-O(3) bond length is 1.55 Å. The P(1)-O(4) bond length is 1.54 Å. The P(1)-O(6) bond length is 1.57 Å. In the second P site, P(2) is bonded to one O(2), one O(5), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Ni(2)O6 octahedra, corners with two equivalent Ni(1)O5 square pyramids, and  an edgeedge with one Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-57°. The P(2)-O(2) bond length is 1.52 Å. The P(2)-O(5) bond length is 1.59 Å. The P(2)-O(7) bond length is 1.58 Å. The P(2)-O(8) bond length is 1.56 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), one Ni(1), and one P(1) atom to form distorted edge-sharing OSr2NiP trigonal pyramids. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent Sr(1) and one P(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sr(1), one Ni(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Sr(1), one Ni(2), and one P(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Sr(1), one Ni(1), one Ni(2), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Ni(1), one Ni(2), and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ni(1), one Ni(2), and one P(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Sr(1), two equivalent Ni(2), and one P(2) atom.