CaNiAsO5 is Esseneite-like structured and crystallizes in the orthorhombic P2_12_12_1 space group. Ca(1) is bonded in a 8-coordinate geometry to one O(1), one O(5), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Ni(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(5) atoms to form NiO6 octahedra that share corners with four equivalent As(1)O4 tetrahedra and edges with two equivalent Ni(1)O6 octahedra. As(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AsO4 tetrahedra that share corners with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-62°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), two equivalent Ni(1), and one As(1) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ca(1) and one As(1) atom. In the third O site, O(3) is bonded to two equivalent Ca(1), one Ni(1), and one As(1) atom to form a mixture of distorted corner and edge-sharing OCa2NiAs tetrahedra. In the fourth O site, O(4) is bonded to two equivalent Ca(1), one Ni(1), and one As(1) atom to form a mixture of distorted corner and edge-sharing OCa2NiAs trigonal pyramids. In the fifth O site, O(5) is bonded in a trigonal non-coplanar geometry to one Ca(1) and two equivalent Ni(1) atoms.
CaNiAsO5 is Esseneite-like structured and crystallizes in the orthorhombic P2_12_12_1 space group. Ca(1) is bonded in a 8-coordinate geometry to one O(1), one O(5), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. The Ca(1)-O(1) bond length is 2.73 Å. The Ca(1)-O(5) bond length is 2.30 Å. There is one shorter (2.40 Å) and one longer (2.49 Å) Ca(1)-O(2) bond length. There is one shorter (2.55 Å) and one longer (2.58 Å) Ca(1)-O(3) bond length. There is one shorter (2.45 Å) and one longer (2.65 Å) Ca(1)-O(4) bond length. Ni(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(5) atoms to form NiO6 octahedra that share corners with four equivalent As(1)O4 tetrahedra and edges with two equivalent Ni(1)O6 octahedra. The Ni(1)-O(3) bond length is 2.09 Å. The Ni(1)-O(4) bond length is 2.06 Å. Both Ni(1)-O(1) bond lengths are 2.07 Å. There is one shorter (1.85 Å) and one longer (1.86 Å) Ni(1)-O(5) bond length. As(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AsO4 tetrahedra that share corners with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-62°. The As(1)-O(1) bond length is 1.75 Å. The As(1)-O(2) bond length is 1.70 Å. The As(1)-O(3) bond length is 1.73 Å. The As(1)-O(4) bond length is 1.73 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), two equivalent Ni(1), and one As(1) atom. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ca(1) and one As(1) atom. In the third O site, O(3) is bonded to two equivalent Ca(1), one Ni(1), and one As(1) atom to form a mixture of distorted corner and edge-sharing OCa2NiAs tetrahedra. In the fourth O site, O(4) is bonded to two equivalent Ca(1), one Ni(1), and one As(1) atom to form a mixture of distorted corner and edge-sharing OCa2NiAs trigonal pyramids. In the fifth O site, O(5) is bonded in a trigonal non-coplanar geometry to one Ca(1) and two equivalent Ni(1) atoms.