Eu2Y2O5 crystallizes in the monoclinic P2 space group. There are four inequivalent Eu sites. In the first Eu site, Eu(1) is bonded to one O(1), one O(2), one O(5), and two equivalent O(11) atoms to form a mixture of edge and corner-sharing EuO5 trigonal bipyramids. In the second Eu site, Eu(2) is bonded to one O(1), one O(3), one O(5), and two equivalent O(12) atoms to form a mixture of edge and corner-sharing EuO5 trigonal bipyramids. In the third Eu site, Eu(3) is bonded to one O(7), one O(8), one O(9), and two equivalent O(4) atoms to form a mixture of edge and corner-sharing EuO5 trigonal bipyramids. In the fourth Eu site, Eu(4) is bonded to one O(6), one O(7), one O(8), and two equivalent O(10) atoms to form a mixture of edge and corner-sharing EuO5 trigonal bipyramids. There are four inequivalent Y sites. In the first Y site, Y(1) is bonded in a 6-coordinate geometry to one O(12), one O(6), two equivalent O(1), and two equivalent O(3) atoms. In the second Y site, Y(2) is bonded in a 6-coordinate geometry to one O(10), one O(2), two equivalent O(6), and two equivalent O(7) atoms. In the third Y site, Y(3) is bonded in a 6-coordinate geometry to one O(11), one O(9), two equivalent O(2), and two equivalent O(5) atoms. In the fourth Y site, Y(4) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(8), and two equivalent O(9) atoms. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Eu(1), one Eu(2), and two equivalent Y(1) atoms to form OEu2Y2 tetrahedra that share corners with two equivalent O(11)Eu4Y2 octahedra,  a cornercorner with one O(2)EuY3 tetrahedra, corners with two equivalent O(1)Eu2Y2 tetrahedra, corners with two equivalent O(6)EuY3 tetrahedra, corners with three equivalent O(3)EuY3 tetrahedra, edges with two equivalent O(12)Eu4Y2 octahedra,  an edgeedge with one O(5)Eu2Y2 tetrahedra, and  an edgeedge with one O(3)EuY3 tetrahedra. The corner-sharing octahedral tilt angles range from 44-52°. In the second O site, O(2) is bonded to one Eu(1), one Y(2), and two equivalent Y(3) atoms to form OEuY3 tetrahedra that share  a cornercorner with one O(10)Eu4Y2 octahedra,  a cornercorner with one O(1)Eu2Y2 tetrahedra, corners with two equivalent O(7)Eu2Y2 tetrahedra, corners with two equivalent O(2)EuY3 tetrahedra, corners with two equivalent O(6)EuY3 tetrahedra, corners with two equivalent O(9)EuY3 tetrahedra, corners with three equivalent O(5)Eu2Y2 tetrahedra, edges with two equivalent O(11)Eu4Y2 octahedra, and  an edgeedge with one O(5)Eu2Y2 tetrahedra. The corner-sharing octahedral tilt angles are 14°. In the third O site, O(3) is bonded to one Eu(2), one Y(4), and two equivalent Y(1) atoms to form OEuY3 tetrahedra that share  a cornercorner with one O(4)Eu4Y2 octahedra,  a cornercorner with one O(5)Eu2Y2 tetrahedra, corners with two equivalent O(8)Eu2Y2 tetrahedra, corners with two equivalent O(3)EuY3 tetrahedra, corners with two equivalent O(6)EuY3 tetrahedra, corners with two equivalent O(9)EuY3 tetrahedra, corners with three equivalent O(1)Eu2Y2 tetrahedra, edges with two equivalent O(12)Eu4Y2 octahedra, and  an edgeedge with one O(1)Eu2Y2 tetrahedra. The corner-sharing octahedral tilt angles are 14°. In the fourth O site, O(4) is bonded to four equivalent Eu(3) and two equivalent Y(4) atoms to form OEu4Y2 octahedra that share corners with two equivalent O(3)EuY3 tetrahedra, corners with four equivalent O(7)Eu2Y2 tetrahedra, edges with two equivalent O(4)Eu4Y2 octahedra, edges with four equivalent O(8)Eu2Y2 tetrahedra, and edges with four equivalent O(9)EuY3 tetrahedra. In the fifth O site, O(5) is bonded to one Eu(1), one Eu(2), and two equivalent Y(3) atoms to form OEu2Y2 tetrahedra that share corners with two equivalent O(12)Eu4Y2 octahedra,  a cornercorner with one O(3)EuY3 tetrahedra, corners with two equivalent O(5)Eu2Y2 tetrahedra, corners with two equivalent O(9)EuY3 tetrahedra, corners with three equivalent O(2)EuY3 tetrahedra, edges with two equivalent O(11)Eu4Y2 octahedra,  an edgeedge with one O(1)Eu2Y2 tetrahedra, and  an edgeedge with one O(2)EuY3 tetrahedra. The corner-sharing octahedral tilt angles range from 44-51°. In the sixth O site, O(6) is bonded to one Eu(4), one Y(1), and two equivalent Y(2) atoms to form OEuY3 tetrahedra that share  a cornercorner with one O(12)Eu4Y2 octahedra,  a cornercorner with one O(8)Eu2Y2 tetrahedra, corners with two equivalent O(1)Eu2Y2 tetrahedra, corners with two equivalent O(2)EuY3 tetrahedra, corners with two equivalent O(3)EuY3 tetrahedra, corners with two equivalent O(6)EuY3 tetrahedra, corners with three equivalent O(7)Eu2Y2 tetrahedra, edges with two equivalent O(10)Eu4Y2 octahedra, and  an edgeedge with one O(7)Eu2Y2 tetrahedra. The corner-sharing octahedral tilt angles are 14°. In the seventh O site, O(7) is bonded to one Eu(3), one Eu(4), and two equivalent Y(2) atoms to form OEu2Y2 tetrahedra that share corners with two equivalent O(4)Eu4Y2 octahedra,  a cornercorner with one O(9)EuY3 tetrahedra, corners with two equivalent O(7)Eu2Y2 tetrahedra, corners with two equivalent O(2)EuY3 tetrahedra, corners with three equivalent O(6)EuY3 tetrahedra, edges with two equivalent O(10)Eu4Y2 octahedra,  an edgeedge with one O(8)Eu2Y2 tetrahedra, and  an edgeedge with one O(6)EuY3 tetrahedra. The corner-sharing octahedral tilt angles range from 45-51°. In the eighth O site, O(8) is bonded to one Eu(3), one Eu(4), and two equivalent Y(4) atoms to form OEu2Y2 tetrahedra that share corners with two equivalent O(10)Eu4Y2 octahedra,  a cornercorner with one O(6)EuY3 tetrahedra, corners with two equivalent O(8)Eu2Y2 tetrahedra, corners with two equivalent O(3)EuY3 tetrahedra, corners with three equivalent O(9)EuY3 tetrahedra, edges with two equivalent O(4)Eu4Y2 octahedra,  an edgeedge with one O(7)Eu2Y2 tetrahedra, and  an edgeedge with one O(9)EuY3 tetrahedra. The corner-sharing octahedral tilt angles range from 45-50°. In the ninth O site, O(9) is bonded to one Eu(3), one Y(3), and two equivalent Y(4) atoms to form OEuY3 tetrahedra that share  a cornercorner with one O(11)Eu4Y2 octahedra,  a cornercorner with one O(7)Eu2Y2 tetrahedra, corners with two equivalent O(5)Eu2Y2 tetrahedra, corners with two equivalent O(2)EuY3 tetrahedra, corners with two equivalent O(3)EuY3 tetrahedra, corners with two equivalent O(9)EuY3 tetrahedra, corners with three equivalent O(8)Eu2Y2 tetrahedra, edges with two equivalent O(4)Eu4Y2 octahedra, and  an edgeedge with one O(8)Eu2Y2 tetrahedra. The corner-sharing octahedral tilt angles are 14°. In the tenth O site, O(10) is bonded to four equivalent Eu(4) and two equivalent Y(2) atoms to form OEu4Y2 octahedra that share corners with two equivalent O(2)EuY3 tetrahedra, corners with four equivalent O(8)Eu2Y2 tetrahedra, edges with two equivalent O(10)Eu4Y2 octahedra, edges with four equivalent O(7)Eu2Y2 tetrahedra, and edges with four equivalent O(6)EuY3 tetrahedra. In the eleventh O site, O(11) is bonded to four equivalent Eu(1) and two equivalent Y(3) atoms to form OEu4Y2 octahedra that share corners with two equivalent O(9)EuY3 tetrahedra, corners with four equivalent O(1)Eu2Y2 tetrahedra, edges with two equivalent O(11)Eu4Y2 octahedra, edges with four equivalent O(5)Eu2Y2 tetrahedra, and edges with four equivalent O(2)EuY3 tetrahedra. In the twelfth O site, O(12) is bonded to four equivalent Eu(2) and two equivalent Y(1) atoms to form OEu4Y2 octahedra that share corners with two equivalent O(6)EuY3 tetrahedra, corners with four equivalent O(5)Eu2Y2 tetrahedra, edges with two equivalent O(12)Eu4Y2 octahedra, edges with four equivalent O(1)Eu2Y2 tetrahedra, and edges with four equivalent O(3)EuY3 tetrahedra.
Eu2Y2O5 crystallizes in the monoclinic P2 space group. There are four inequivalent Eu sites. In the first Eu site, Eu(1) is bonded to one O(1), one O(2), one O(5), and two equivalent O(11) atoms to form a mixture of edge and corner-sharing EuO5 trigonal bipyramids. The Eu(1)-O(1) bond length is 2.35 Å. The Eu(1)-O(2) bond length is 2.44 Å. The Eu(1)-O(5) bond length is 2.46 Å. There is one shorter (2.43 Å) and one longer (2.45 Å) Eu(1)-O(11) bond length. In the second Eu site, Eu(2) is bonded to one O(1), one O(3), one O(5), and two equivalent O(12) atoms to form a mixture of edge and corner-sharing EuO5 trigonal bipyramids. The Eu(2)-O(1) bond length is 2.46 Å. The Eu(2)-O(3) bond length is 2.45 Å. The Eu(2)-O(5) bond length is 2.35 Å. There is one shorter (2.44 Å) and one longer (2.45 Å) Eu(2)-O(12) bond length. In the third Eu site, Eu(3) is bonded to one O(7), one O(8), one O(9), and two equivalent O(4) atoms to form a mixture of edge and corner-sharing EuO5 trigonal bipyramids. The Eu(3)-O(7) bond length is 2.36 Å. The Eu(3)-O(8) bond length is 2.47 Å. The Eu(3)-O(9) bond length is 2.45 Å. There is one shorter (2.44 Å) and one longer (2.45 Å) Eu(3)-O(4) bond length. In the fourth Eu site, Eu(4) is bonded to one O(6), one O(7), one O(8), and two equivalent O(10) atoms to form a mixture of edge and corner-sharing EuO5 trigonal bipyramids. The Eu(4)-O(6) bond length is 2.45 Å. The Eu(4)-O(7) bond length is 2.46 Å. The Eu(4)-O(8) bond length is 2.35 Å. There is one shorter (2.43 Å) and one longer (2.45 Å) Eu(4)-O(10) bond length. There are four inequivalent Y sites. In the first Y site, Y(1) is bonded in a 6-coordinate geometry to one O(12), one O(6), two equivalent O(1), and two equivalent O(3) atoms. The Y(1)-O(12) bond length is 2.81 Å. The Y(1)-O(6) bond length is 2.23 Å. Both Y(1)-O(1) bond lengths are 2.27 Å. There is one shorter (2.37 Å) and one longer (2.39 Å) Y(1)-O(3) bond length. In the second Y site, Y(2) is bonded in a 6-coordinate geometry to one O(10), one O(2), two equivalent O(6), and two equivalent O(7) atoms. The Y(2)-O(10) bond length is 2.83 Å. The Y(2)-O(2) bond length is 2.23 Å. There is one shorter (2.37 Å) and one longer (2.40 Å) Y(2)-O(6) bond length. There is one shorter (2.26 Å) and one longer (2.27 Å) Y(2)-O(7) bond length. In the third Y site, Y(3) is bonded in a 6-coordinate geometry to one O(11), one O(9), two equivalent O(2), and two equivalent O(5) atoms. The Y(3)-O(11) bond length is 2.82 Å. The Y(3)-O(9) bond length is 2.23 Å. There is one shorter (2.37 Å) and one longer (2.39 Å) Y(3)-O(2) bond length. Both Y(3)-O(5) bond lengths are 2.27 Å. In the fourth Y site, Y(4) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(8), and two equivalent O(9) atoms. The Y(4)-O(3) bond length is 2.24 Å. The Y(4)-O(4) bond length is 2.83 Å. Both Y(4)-O(8) bond lengths are 2.27 Å. There is one shorter (2.37 Å) and one longer (2.39 Å) Y(4)-O(9) bond length. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Eu(1), one Eu(2), and two equivalent Y(1) atoms to form OEu2Y2 tetrahedra that share corners with two equivalent O(11)Eu4Y2 octahedra,  a cornercorner with one O(2)EuY3 tetrahedra, corners with two equivalent O(1)Eu2Y2 tetrahedra, corners with two equivalent O(6)EuY3 tetrahedra, corners with three equivalent O(3)EuY3 tetrahedra, edges with two equivalent O(12)Eu4Y2 octahedra,  an edgeedge with one O(5)Eu2Y2 tetrahedra, and  an edgeedge with one O(3)EuY3 tetrahedra. The corner-sharing octahedral tilt angles range from 44-52°. In the second O site, O(2) is bonded to one Eu(1), one Y(2), and two equivalent Y(3) atoms to form OEuY3 tetrahedra that share  a cornercorner with one O(10)Eu4Y2 octahedra,  a cornercorner with one O(1)Eu2Y2 tetrahedra, corners with two equivalent O(7)Eu2Y2 tetrahedra, corners with two equivalent O(2)EuY3 tetrahedra, corners with two equivalent O(6)EuY3 tetrahedra, corners with two equivalent O(9)EuY3 tetrahedra, corners with three equivalent O(5)Eu2Y2 tetrahedra, edges with two equivalent O(11)Eu4Y2 octahedra, and  an edgeedge with one O(5)Eu2Y2 tetrahedra. The corner-sharing octahedral tilt angles are 14°. In the third O site, O(3) is bonded to one Eu(2), one Y(4), and two equivalent Y(1) atoms to form OEuY3 tetrahedra that share  a cornercorner with one O(4)Eu4Y2 octahedra,  a cornercorner with one O(5)Eu2Y2 tetrahedra, corners with two equivalent O(8)Eu2Y2 tetrahedra, corners with two equivalent O(3)EuY3 tetrahedra, corners with two equivalent O(6)EuY3 tetrahedra, corners with two equivalent O(9)EuY3 tetrahedra, corners with three equivalent O(1)Eu2Y2 tetrahedra, edges with two equivalent O(12)Eu4Y2 octahedra, and  an edgeedge with one O(1)Eu2Y2 tetrahedra. The corner-sharing octahedral tilt angles are 14°. In the fourth O site, O(4) is bonded to four equivalent Eu(3) and two equivalent Y(4) atoms to form OEu4Y2 octahedra that share corners with two equivalent O(3)EuY3 tetrahedra, corners with four equivalent O(7)Eu2Y2 tetrahedra, edges with two equivalent O(4)Eu4Y2 octahedra, edges with four equivalent O(8)Eu2Y2 tetrahedra, and edges with four equivalent O(9)EuY3 tetrahedra. In the fifth O site, O(5) is bonded to one Eu(1), one Eu(2), and two equivalent Y(3) atoms to form OEu2Y2 tetrahedra that share corners with two equivalent O(12)Eu4Y2 octahedra,  a cornercorner with one O(3)EuY3 tetrahedra, corners with two equivalent O(5)Eu2Y2 tetrahedra, corners with two equivalent O(9)EuY3 tetrahedra, corners with three equivalent O(2)EuY3 tetrahedra, edges with two equivalent O(11)Eu4Y2 octahedra,  an edgeedge with one O(1)Eu2Y2 tetrahedra, and  an edgeedge with one O(2)EuY3 tetrahedra. The corner-sharing octahedral tilt angles range from 44-51°. In the sixth O site, O(6) is bonded to one Eu(4), one Y(1), and two equivalent Y(2) atoms to form OEuY3 tetrahedra that share  a cornercorner with one O(12)Eu4Y2 octahedra,  a cornercorner with one O(8)Eu2Y2 tetrahedra, corners with two equivalent O(1)Eu2Y2 tetrahedra, corners with two equivalent O(2)EuY3 tetrahedra, corners with two equivalent O(3)EuY3 tetrahedra, corners with two equivalent O(6)EuY3 tetrahedra, corners with three equivalent O(7)Eu2Y2 tetrahedra, edges with two equivalent O(10)Eu4Y2 octahedra, and  an edgeedge with one O(7)Eu2Y2 tetrahedra. The corner-sharing octahedral tilt angles are 14°. In the seventh O site, O(7) is bonded to one Eu(3), one Eu(4), and two equivalent Y(2) atoms to form OEu2Y2 tetrahedra that share corners with two equivalent O(4)Eu4Y2 octahedra,  a cornercorner with one O(9)EuY3 tetrahedra, corners with two equivalent O(7)Eu2Y2 tetrahedra, corners with two equivalent O(2)EuY3 tetrahedra, corners with three equivalent O(6)EuY3 tetrahedra, edges with two equivalent O(10)Eu4Y2 octahedra,  an edgeedge with one O(8)Eu2Y2 tetrahedra, and  an edgeedge with one O(6)EuY3 tetrahedra. The corner-sharing octahedral tilt angles range from 45-51°. In the eighth O site, O(8) is bonded to one Eu(3), one Eu(4), and two equivalent Y(4) atoms to form OEu2Y2 tetrahedra that share corners with two equivalent O(10)Eu4Y2 octahedra,  a cornercorner with one O(6)EuY3 tetrahedra, corners with two equivalent O(8)Eu2Y2 tetrahedra, corners with two equivalent O(3)EuY3 tetrahedra, corners with three equivalent O(9)EuY3 tetrahedra, edges with two equivalent O(4)Eu4Y2 octahedra,  an edgeedge with one O(7)Eu2Y2 tetrahedra, and  an edgeedge with one O(9)EuY3 tetrahedra. The corner-sharing octahedral tilt angles range from 45-50°. In the ninth O site, O(9) is bonded to one Eu(3), one Y(3), and two equivalent Y(4) atoms to form OEuY3 tetrahedra that share  a cornercorner with one O(11)Eu4Y2 octahedra,  a cornercorner with one O(7)Eu2Y2 tetrahedra, corners with two equivalent O(5)Eu2Y2 tetrahedra, corners with two equivalent O(2)EuY3 tetrahedra, corners with two equivalent O(3)EuY3 tetrahedra, corners with two equivalent O(9)EuY3 tetrahedra, corners with three equivalent O(8)Eu2Y2 tetrahedra, edges with two equivalent O(4)Eu4Y2 octahedra, and  an edgeedge with one O(8)Eu2Y2 tetrahedra. The corner-sharing octahedral tilt angles are 14°. In the tenth O site, O(10) is bonded to four equivalent Eu(4) and two equivalent Y(2) atoms to form OEu4Y2 octahedra that share corners with two equivalent O(2)EuY3 tetrahedra, corners with four equivalent O(8)Eu2Y2 tetrahedra, edges with two equivalent O(10)Eu4Y2 octahedra, edges with four equivalent O(7)Eu2Y2 tetrahedra, and edges with four equivalent O(6)EuY3 tetrahedra. In the eleventh O site, O(11) is bonded to four equivalent Eu(1) and two equivalent Y(3) atoms to form OEu4Y2 octahedra that share corners with two equivalent O(9)EuY3 tetrahedra, corners with four equivalent O(1)Eu2Y2 tetrahedra, edges with two equivalent O(11)Eu4Y2 octahedra, edges with four equivalent O(5)Eu2Y2 tetrahedra, and edges with four equivalent O(2)EuY3 tetrahedra. In the twelfth O site, O(12) is bonded to four equivalent Eu(2) and two equivalent Y(1) atoms to form OEu4Y2 octahedra that share corners with two equivalent O(6)EuY3 tetrahedra, corners with four equivalent O(5)Eu2Y2 tetrahedra, edges with two equivalent O(12)Eu4Y2 octahedra, edges with four equivalent O(1)Eu2Y2 tetrahedra, and edges with four equivalent O(3)EuY3 tetrahedra.