Ba2NdAlO5 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to one O(3), one O(4), two equivalent O(1), two equivalent O(5), and three equivalent O(2) atoms. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one O(2), one O(5), two equivalent O(1), two equivalent O(3), and three equivalent O(4) atoms. Nd(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form NdO6 octahedra that share corners with two equivalent Nd(1)O6 octahedra and corners with four equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 6°. 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 Nd(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 16-65°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Nd(1) atoms to form distorted face-sharing OBa4Nd2 octahedra. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Ba(2), three equivalent Ba(1), one Nd(1), and one Al(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ba(1), two equivalent Ba(2), one Nd(1), and one Al(1) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to one Ba(1), three equivalent Ba(2), one Nd(1), and one Al(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ba(2), two equivalent Ba(1), one Nd(1), and one Al(1) atom.
Ba2NdAlO5 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to one O(3), one O(4), two equivalent O(1), two equivalent O(5), and three equivalent O(2) atoms. The Ba(1)-O(3) bond length is 2.80 Å. The Ba(1)-O(4) bond length is 2.70 Å. There is one shorter (2.84 Å) and one longer (2.95 Å) Ba(1)-O(1) bond length. There is one shorter (2.81 Å) and one longer (3.25 Å) Ba(1)-O(5) bond length. There are a spread of Ba(1)-O(2) bond distances ranging from 3.01-3.26 Å. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one O(2), one O(5), two equivalent O(1), two equivalent O(3), and three equivalent O(4) atoms. The Ba(2)-O(2) bond length is 2.68 Å. The Ba(2)-O(5) bond length is 2.82 Å. There is one shorter (2.78 Å) and one longer (2.96 Å) Ba(2)-O(1) bond length. There is one shorter (2.87 Å) and one longer (3.44 Å) Ba(2)-O(3) bond length. There are a spread of Ba(2)-O(4) bond distances ranging from 3.11-3.50 Å. Nd(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form NdO6 octahedra that share corners with two equivalent Nd(1)O6 octahedra and corners with four equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 6°. The Nd(1)-O(2) bond length is 2.45 Å. The Nd(1)-O(3) bond length is 2.37 Å. The Nd(1)-O(4) bond length is 2.53 Å. The Nd(1)-O(5) bond length is 2.36 Å. There is one shorter (2.31 Å) and one longer (2.33 Å) Nd(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 Nd(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 16-65°. The Al(1)-O(2) bond length is 1.80 Å. The Al(1)-O(3) bond length is 1.79 Å. The Al(1)-O(4) bond length is 1.79 Å. The Al(1)-O(5) bond length is 1.79 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Nd(1) atoms to form distorted face-sharing OBa4Nd2 octahedra. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Ba(2), three equivalent Ba(1), one Nd(1), and one Al(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ba(1), two equivalent Ba(2), one Nd(1), and one Al(1) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to one Ba(1), three equivalent Ba(2), one Nd(1), and one Al(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ba(2), two equivalent Ba(1), one Nd(1), and one Al(1) atom.