Ba5Er2ZrAl2O13 crystallizes in the hexagonal P6_3/mmc space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted q6 geometry to three equivalent O(1) and six equivalent O(2) atoms. In the second Ba site, Ba(2) is bonded in a 12-coordinate geometry to three equivalent O(2) and nine equivalent O(1) atoms. In the third Ba site, Ba(3) is bonded in a 6-coordinate geometry to six equivalent O(2) atoms. Er(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form ErO6 octahedra that share corners with three equivalent Zr(1)O6 octahedra and corners with three equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 1°. Zr(1) is bonded to six equivalent O(1) atoms to form ZrO6 octahedra that share corners with six equivalent Er(1)O6 octahedra. The corner-sharing octahedral tilt angles are 1°. Al(1) is bonded to one O(3) and three equivalent O(2) atoms to form AlO4 tetrahedra that share corners with three equivalent Er(1)O6 octahedra and  a cornercorner with one Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 18°. There are three inequivalent O sites. In the first O site, O(3) is bonded in a linear geometry to two equivalent Al(1) atoms. In the second O site, O(1) is bonded to one Ba(1), three equivalent Ba(2), one Er(1), and one Zr(1) atom to form a mixture of distorted face, corner, and edge-sharing OBa4ErZr octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the third O site, O(2) is bonded in a 2-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Er(1), and one Al(1) atom.
Ba5Er2ZrAl2O13 crystallizes in the hexagonal P6_3/mmc space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted q6 geometry to three equivalent O(1) and six equivalent O(2) atoms. All Ba(1)-O(1) bond lengths are 2.77 Å. All Ba(1)-O(2) bond lengths are 3.05 Å. In the second Ba site, Ba(2) is bonded in a 12-coordinate geometry to three equivalent O(2) and nine equivalent O(1) atoms. All Ba(2)-O(2) bond lengths are 3.38 Å. There are three shorter (2.91 Å) and six longer (3.02 Å) Ba(2)-O(1) bond lengths. In the third Ba site, Ba(3) is bonded in a 6-coordinate geometry to six equivalent O(2) atoms. All Ba(3)-O(2) bond lengths are 2.93 Å. Er(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form ErO6 octahedra that share corners with three equivalent Zr(1)O6 octahedra and corners with three equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 1°. All Er(1)-O(1) bond lengths are 2.23 Å. All Er(1)-O(2) bond lengths are 2.25 Å. Zr(1) is bonded to six equivalent O(1) atoms to form ZrO6 octahedra that share corners with six equivalent Er(1)O6 octahedra. The corner-sharing octahedral tilt angles are 1°. All Zr(1)-O(1) bond lengths are 2.12 Å. Al(1) is bonded to one O(3) and three equivalent O(2) atoms to form AlO4 tetrahedra that share corners with three equivalent Er(1)O6 octahedra and  a cornercorner with one Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 18°. The Al(1)-O(3) bond length is 1.74 Å. All Al(1)-O(2) bond lengths are 1.78 Å. There are three inequivalent O sites. In the first O site, O(3) is bonded in a linear geometry to two equivalent Al(1) atoms. In the second O site, O(1) is bonded to one Ba(1), three equivalent Ba(2), one Er(1), and one Zr(1) atom to form a mixture of distorted face, corner, and edge-sharing OBa4ErZr octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the third O site, O(2) is bonded in a 2-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Er(1), and one Al(1) atom.