CaAlTaO5 crystallizes in the monoclinic Cc space group. Ca(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), two equivalent O(4), and two equivalent O(5) atoms. Ta(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with four equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 39°. Al(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form AlO4 tetrahedra that share corners with four equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-53°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ca(1), one Ta(1), and one Al(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Ca(1), one Ta(1), and one Al(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Ta(1), and one Al(1) atom. In the fifth O site, O(5) is bonded to two equivalent Ca(1), one Ta(1), and one Al(1) atom to form distorted corner-sharing OCa2TaAl tetrahedra.
CaAlTaO5 crystallizes in the monoclinic Cc space group. Ca(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), two equivalent O(4), and two equivalent O(5) atoms. The Ca(1)-O(1) bond length is 2.34 Å. The Ca(1)-O(2) bond length is 2.49 Å. The Ca(1)-O(3) bond length is 2.43 Å. There is one shorter (2.47 Å) and one longer (2.91 Å) Ca(1)-O(4) bond length. There is one shorter (2.46 Å) and one longer (2.63 Å) Ca(1)-O(5) bond length. Ta(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with four equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 39°. The Ta(1)-O(2) bond length is 1.99 Å. The Ta(1)-O(3) bond length is 1.99 Å. The Ta(1)-O(4) bond length is 2.00 Å. The Ta(1)-O(5) bond length is 2.04 Å. There is one shorter (1.97 Å) and one longer (1.99 Å) Ta(1)-O(1) bond length. Al(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form AlO4 tetrahedra that share corners with four equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-53°. The Al(1)-O(2) bond length is 1.77 Å. The Al(1)-O(3) bond length is 1.77 Å. The Al(1)-O(4) bond length is 1.78 Å. The Al(1)-O(5) bond length is 1.78 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ca(1), one Ta(1), and one Al(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Ca(1), one Ta(1), and one Al(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Ta(1), and one Al(1) atom. In the fifth O site, O(5) is bonded to two equivalent Ca(1), one Ta(1), and one Al(1) atom to form distorted corner-sharing OCa2TaAl tetrahedra.