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CaNi2 is Cubic Laves structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Ca is bonded in a 12-coordinate geometry to twelve equivalent Ni atoms. All Ca–Ni bond lengths are 2.97 Å. Ni is bonded to six equivalent Ca and six equivalent Ni atoms to form a mixture of edge, face, and corner-sharing NiCa6Ni6 cuboctahedra. All Ni–Ni bond lengths are 2.54 Å.
CaNi2(P2O7)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.23–2.74 Å. There are two inequivalent Ni3+ sites. In the first Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 2.03–2.19 Å. In the second Ni3+ site, Ni3+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 2.05–2.14 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three NiO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–61°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three NiO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 42–57°. There are a spread of P–O bond distances ranging from 1.52–1.60 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three NiO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 40–55°. There are a spread of P–O bond distances ranging from 1.52–1.61 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three NiO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 27–50°. There are a spread of P–O bond distances ranging from 1.52–1.61 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ni3+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ni3+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ni3+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Ni3+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to one Ca2+, one Ni3+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ni3+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ca2+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ca2+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ni3+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to one Ca2+, two Ni3+, and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ni3+ and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a 1-coordinate geometry to one Ca2+, one Ni3+, and one P5+ atom.