SrEr2O4 crystallizes in the monoclinic Pm space group. Sr(1) is bonded in a distorted trigonal non-coplanar geometry to one O(1), one O(3), and two equivalent O(4) atoms. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. In the second Er site, Er(2) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted edge-sharing ErO5 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Sr(1), two equivalent Er(1), and two equivalent Er(2) atoms. In the second O site, O(2) is bonded in a square co-planar geometry to two equivalent Er(1) and two equivalent Er(2) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Sr(1) and two equivalent Er(1) atoms. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to two equivalent Sr(1) and one Er(2) atom.
SrEr2O4 crystallizes in the monoclinic Pm space group. Sr(1) is bonded in a distorted trigonal non-coplanar geometry to one O(1), one O(3), and two equivalent O(4) atoms. The Sr(1)-O(1) bond length is 3.13 Å. The Sr(1)-O(3) bond length is 2.33 Å. Both Sr(1)-O(4) bond lengths are 2.28 Å. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Both Er(1)-O(1) bond lengths are 2.43 Å. Both Er(1)-O(2) bond lengths are 2.43 Å. Both Er(1)-O(3) bond lengths are 2.15 Å. In the second Er site, Er(2) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted edge-sharing ErO5 trigonal bipyramids. The Er(2)-O(4) bond length is 2.05 Å. Both Er(2)-O(1) bond lengths are 2.27 Å. Both Er(2)-O(2) bond lengths are 2.27 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Sr(1), two equivalent Er(1), and two equivalent Er(2) atoms. In the second O site, O(2) is bonded in a square co-planar geometry to two equivalent Er(1) and two equivalent Er(2) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Sr(1) and two equivalent Er(1) atoms. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to two equivalent Sr(1) and one Er(2) atom.