Eu2Pt2O7 crystallizes in the trigonal R-3m space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a distorted body-centered cubic geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. In the second Eu site, Eu(2) is bonded in a body-centered cubic geometry to two equivalent O(1) and six equivalent O(3) atoms. There are two inequivalent Pt sites. In the first Pt site, Pt(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form corner-sharing PtO6 octahedra. The corner-sharing octahedral tilt angles are 51°. In the second Pt site, Pt(2) is bonded to six equivalent O(2) atoms to form corner-sharing PtO6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Eu(2) and three equivalent Eu(1) atoms to form OEu4 tetrahedra that share corners with four equivalent O(1)Eu4 tetrahedra, corners with six equivalent O(2)Eu2Pt2 tetrahedra, corners with six equivalent O(3)Eu2Pt2 tetrahedra, edges with three equivalent O(2)Eu2Pt2 tetrahedra, and edges with three equivalent O(3)Eu2Pt2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Eu(1), one Pt(1), and one Pt(2) atom to form distorted OEu2Pt2 tetrahedra that share corners with two equivalent O(1)Eu4 tetrahedra, corners with four equivalent O(3)Eu2Pt2 tetrahedra, corners with eight equivalent O(2)Eu2Pt2 tetrahedra,  an edgeedge with one O(1)Eu4 tetrahedra, edges with two equivalent O(2)Eu2Pt2 tetrahedra, and edges with two equivalent O(3)Eu2Pt2 tetrahedra. In the third O site, O(3) is bonded to one Eu(1), one Eu(2), and two equivalent Pt(1) atoms to form distorted OEu2Pt2 tetrahedra that share corners with two equivalent O(1)Eu4 tetrahedra, corners with four equivalent O(2)Eu2Pt2 tetrahedra, corners with eight equivalent O(3)Eu2Pt2 tetrahedra,  an edgeedge with one O(1)Eu4 tetrahedra, edges with two equivalent O(2)Eu2Pt2 tetrahedra, and edges with two equivalent O(3)Eu2Pt2 tetrahedra.
Eu2Pt2O7 crystallizes in the trigonal R-3m space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a distorted body-centered cubic geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. Both Eu(1)-O(1) bond lengths are 2.24 Å. Both Eu(1)-O(3) bond lengths are 2.50 Å. All Eu(1)-O(2) bond lengths are 2.51 Å. In the second Eu site, Eu(2) is bonded in a body-centered cubic geometry to two equivalent O(1) and six equivalent O(3) atoms. Both Eu(2)-O(1) bond lengths are 2.24 Å. All Eu(2)-O(3) bond lengths are 2.51 Å. There are two inequivalent Pt sites. In the first Pt site, Pt(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form corner-sharing PtO6 octahedra. The corner-sharing octahedral tilt angles are 51°. Both Pt(1)-O(2) bond lengths are 2.03 Å. All Pt(1)-O(3) bond lengths are 2.03 Å. In the second Pt site, Pt(2) is bonded to six equivalent O(2) atoms to form corner-sharing PtO6 octahedra. The corner-sharing octahedral tilt angles are 51°. All Pt(2)-O(2) bond lengths are 2.02 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Eu(2) and three equivalent Eu(1) atoms to form OEu4 tetrahedra that share corners with four equivalent O(1)Eu4 tetrahedra, corners with six equivalent O(2)Eu2Pt2 tetrahedra, corners with six equivalent O(3)Eu2Pt2 tetrahedra, edges with three equivalent O(2)Eu2Pt2 tetrahedra, and edges with three equivalent O(3)Eu2Pt2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Eu(1), one Pt(1), and one Pt(2) atom to form distorted OEu2Pt2 tetrahedra that share corners with two equivalent O(1)Eu4 tetrahedra, corners with four equivalent O(3)Eu2Pt2 tetrahedra, corners with eight equivalent O(2)Eu2Pt2 tetrahedra,  an edgeedge with one O(1)Eu4 tetrahedra, edges with two equivalent O(2)Eu2Pt2 tetrahedra, and edges with two equivalent O(3)Eu2Pt2 tetrahedra. In the third O site, O(3) is bonded to one Eu(1), one Eu(2), and two equivalent Pt(1) atoms to form distorted OEu2Pt2 tetrahedra that share corners with two equivalent O(1)Eu4 tetrahedra, corners with four equivalent O(2)Eu2Pt2 tetrahedra, corners with eight equivalent O(3)Eu2Pt2 tetrahedra,  an edgeedge with one O(1)Eu4 tetrahedra, edges with two equivalent O(2)Eu2Pt2 tetrahedra, and edges with two equivalent O(3)Eu2Pt2 tetrahedra.