Er2Pt2O5 crystallizes in the tetragonal P4/mmm space group. Er(1) is bonded in a 5-coordinate geometry to one O(2) and four equivalent O(1) atoms. There are two inequivalent Pt sites. In the first Pt site, Pt(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. In the second Pt site, Pt(2) is bonded in a square co-planar geometry to four equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Er(1) and two equivalent Pt(1) atoms to form OEr2Pt2 tetrahedra that share corners with two equivalent O(2)Er2Pt4 octahedra, corners with ten equivalent O(1)Er2Pt2 tetrahedra, and edges with five equivalent O(1)Er2Pt2 tetrahedra. The corner-sharing octahedral tilt angles are 59°. In the second O site, O(2) is bonded to two equivalent Er(1) and four equivalent Pt(2) atoms to form distorted OEr2Pt4 octahedra that share corners with four equivalent O(2)Er2Pt4 octahedra, corners with eight equivalent O(1)Er2Pt2 tetrahedra, and edges with four equivalent O(2)Er2Pt4 octahedra. The corner-sharing octahedra are not tilted.
Er2Pt2O5 crystallizes in the tetragonal P4/mmm space group. Er(1) is bonded in a 5-coordinate geometry to one O(2) and four equivalent O(1) atoms. The Er(1)-O(2) bond length is 2.16 Å. All Er(1)-O(1) bond lengths are 2.19 Å. There are two inequivalent Pt sites. In the first Pt site, Pt(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. All Pt(1)-O(1) bond lengths are 2.24 Å. In the second Pt site, Pt(2) is bonded in a square co-planar geometry to four equivalent O(2) atoms. All Pt(2)-O(2) bond lengths are 2.66 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Er(1) and two equivalent Pt(1) atoms to form OEr2Pt2 tetrahedra that share corners with two equivalent O(2)Er2Pt4 octahedra, corners with ten equivalent O(1)Er2Pt2 tetrahedra, and edges with five equivalent O(1)Er2Pt2 tetrahedra. The corner-sharing octahedral tilt angles are 59°. In the second O site, O(2) is bonded to two equivalent Er(1) and four equivalent Pt(2) atoms to form distorted OEr2Pt4 octahedra that share corners with four equivalent O(2)Er2Pt4 octahedra, corners with eight equivalent O(1)Er2Pt2 tetrahedra, and edges with four equivalent O(2)Er2Pt4 octahedra. The corner-sharing octahedra are not tilted.