Ca2CuAlO5 crystallizes in the orthorhombic Ima2 space group. Ca(1) is bonded in a 8-coordinate geometry to one O(1), three equivalent O(2), and four equivalent O(3) atoms. Cu(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form CuO6 octahedra that share corners with four equivalent Cu(1)O6 octahedra and corners with two equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 15°. Al(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form AlO4 tetrahedra that share corners with two equivalent Cu(1)O6 octahedra and corners with two equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and two equivalent Al(1) atoms to form distorted OCa2Al2 tetrahedra that share corners with eight equivalent O(3)Ca4Cu2 octahedra and corners with two equivalent O(1)Ca2Al2 tetrahedra. The corner-sharing octahedral tilt angles range from 15-87°. In the second O site, O(2) is bonded in a 4-coordinate geometry to three equivalent Ca(1), one Cu(1), and one Al(1) atom. In the third O site, O(3) is bonded to four equivalent Ca(1) and two equivalent Cu(1) atoms to form distorted OCa4Cu2 octahedra that share corners with two equivalent O(3)Ca4Cu2 octahedra, corners with four equivalent O(1)Ca2Al2 tetrahedra, edges with two equivalent O(3)Ca4Cu2 octahedra, and faces with four equivalent O(3)Ca4Cu2 octahedra. The corner-sharing octahedral tilt angles are 1°.
Ca2CuAlO5 crystallizes in the orthorhombic Ima2 space group. Ca(1) is bonded in a 8-coordinate geometry to one O(1), three equivalent O(2), and four equivalent O(3) atoms. The Ca(1)-O(1) bond length is 2.41 Å. There are a spread of Ca(1)-O(2) bond distances ranging from 2.33-2.93 Å. There are a spread of Ca(1)-O(3) bond distances ranging from 2.43-2.60 Å. Cu(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form CuO6 octahedra that share corners with four equivalent Cu(1)O6 octahedra and corners with two equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 15°. Both Cu(1)-O(2) bond lengths are 2.21 Å. There are two shorter (1.94 Å) and two longer (1.95 Å) Cu(1)-O(3) bond lengths. Al(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form AlO4 tetrahedra that share corners with two equivalent Cu(1)O6 octahedra and corners with two equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. Both Al(1)-O(1) bond lengths are 1.80 Å. Both Al(1)-O(2) bond lengths are 1.77 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and two equivalent Al(1) atoms to form distorted OCa2Al2 tetrahedra that share corners with eight equivalent O(3)Ca4Cu2 octahedra and corners with two equivalent O(1)Ca2Al2 tetrahedra. The corner-sharing octahedral tilt angles range from 15-87°. In the second O site, O(2) is bonded in a 4-coordinate geometry to three equivalent Ca(1), one Cu(1), and one Al(1) atom. In the third O site, O(3) is bonded to four equivalent Ca(1) and two equivalent Cu(1) atoms to form distorted OCa4Cu2 octahedra that share corners with two equivalent O(3)Ca4Cu2 octahedra, corners with four equivalent O(1)Ca2Al2 tetrahedra, edges with two equivalent O(3)Ca4Cu2 octahedra, and faces with four equivalent O(3)Ca4Cu2 octahedra. The corner-sharing octahedral tilt angles are 1°.