Er2BaO4 crystallizes in the orthorhombic Pnma space group. Ba(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to one O(1), two equivalent O(3), and three equivalent O(2) atoms to form a mixture of corner and edge-sharing ErO6 octahedra. The corner-sharing octahedral tilt angles range from 50-57°. In the second Er site, Er(2) is bonded to one O(3), two equivalent O(1), and three equivalent O(4) atoms to form a mixture of corner and edge-sharing ErO6 octahedra. The corner-sharing octahedral tilt angles range from 50-57°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Ba(1), one Er(1), and two equivalent Er(2) atoms. In the second O site, O(2) is bonded to two equivalent Ba(1) and three equivalent Er(1) atoms to form a mixture of distorted corner and edge-sharing OBa2Er3 square pyramids. In the third O site, O(3) is bonded to two equivalent Ba(1), one Er(2), and two equivalent Er(1) atoms to form a mixture of distorted corner and edge-sharing OBa2Er3 trigonal bipyramids. In the fourth O site, O(4) is bonded to two equivalent Ba(1) and three equivalent Er(2) atoms to form a mixture of distorted corner and edge-sharing OBa2Er3 trigonal bipyramids.
Er2BaO4 crystallizes in the orthorhombic Pnma space group. Ba(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Both Ba(1)-O(1) bond lengths are 2.92 Å. Both Ba(1)-O(2) bond lengths are 2.71 Å. There is one shorter (2.87 Å) and one longer (2.90 Å) Ba(1)-O(3) bond length. Both Ba(1)-O(4) bond lengths are 2.72 Å. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to one O(1), two equivalent O(3), and three equivalent O(2) atoms to form a mixture of corner and edge-sharing ErO6 octahedra. The corner-sharing octahedral tilt angles range from 50-57°. The Er(1)-O(1) bond length is 2.28 Å. Both Er(1)-O(3) bond lengths are 2.24 Å. There is one shorter (2.27 Å) and two longer (2.31 Å) Er(1)-O(2) bond lengths. In the second Er site, Er(2) is bonded to one O(3), two equivalent O(1), and three equivalent O(4) atoms to form a mixture of corner and edge-sharing ErO6 octahedra. The corner-sharing octahedral tilt angles range from 50-57°. The Er(2)-O(3) bond length is 2.28 Å. Both Er(2)-O(1) bond lengths are 2.28 Å. There is one shorter (2.21 Å) and two longer (2.30 Å) Er(2)-O(4) bond lengths. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Ba(1), one Er(1), and two equivalent Er(2) atoms. In the second O site, O(2) is bonded to two equivalent Ba(1) and three equivalent Er(1) atoms to form a mixture of distorted corner and edge-sharing OBa2Er3 square pyramids. In the third O site, O(3) is bonded to two equivalent Ba(1), one Er(2), and two equivalent Er(1) atoms to form a mixture of distorted corner and edge-sharing OBa2Er3 trigonal bipyramids. In the fourth O site, O(4) is bonded to two equivalent Ba(1) and three equivalent Er(2) atoms to form a mixture of distorted corner and edge-sharing OBa2Er3 trigonal bipyramids.