Eu8Nb5Mn3O28 crystallizes in the monoclinic C2 space group. There are four inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a distorted body-centered cubic geometry to one O(10), one O(11), one O(12), one O(2), one O(3), one O(5), one O(8), and one O(9) atom. In the second Eu site, Eu(2) is bonded in a distorted body-centered cubic geometry to one O(1), one O(10), one O(11), one O(12), one O(4), one O(6), one O(7), and one O(9) atom. In the third Eu site, Eu(3) is bonded to one O(1), one O(10), one O(12), one O(13), one O(2), one O(7), and one O(8) atom to form distorted EuO7 pentagonal bipyramids that share  a cornercorner with one Mn(3)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra,  an edgeedge with one Nb(3)O6 octahedra, and edges with two equivalent Eu(4)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 49-60°. In the fourth Eu site, Eu(4) is bonded to one O(1), one O(11), one O(14), one O(2), one O(7), one O(8), and one O(9) atom to form distorted EuO7 pentagonal bipyramids that share  a cornercorner with one Nb(3)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra,  an edgeedge with one Mn(3)O6 octahedra, and edges with two equivalent Eu(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 48-51°. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(11), one O(13), one O(3), one O(7), and two equivalent O(6) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra, corners with two equivalent Eu(4)O7 pentagonal bipyramids, and  an edgeedge with one Eu(3)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 24-49°. In the second Nb site, Nb(2) is bonded to one O(12), one O(14), one O(4), one O(8), and two equivalent O(5) atoms to form NbO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Eu(3)O7 pentagonal bipyramids, and  an edgeedge with one Eu(4)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 26-44°. In the third Nb site, Nb(3) is bonded to two equivalent O(13), two equivalent O(2), and two equivalent O(3) atoms to form NbO6 octahedra that share corners with four equivalent Nb(1)O6 octahedra, corners with two equivalent Eu(4)O7 pentagonal bipyramids, and edges with two equivalent Eu(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 24-49°. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 4-coordinate geometry to two equivalent O(4) and two equivalent O(9) atoms. In the second Mn site, Mn(2) is bonded in a 4-coordinate geometry to two equivalent O(10), two equivalent O(3), and two equivalent O(6) atoms. In the third Mn site, Mn(3) is bonded to two equivalent O(1), two equivalent O(14), and two equivalent O(4) atoms to form MnO6 octahedra that share corners with four equivalent Nb(2)O6 octahedra, corners with two equivalent Eu(3)O7 pentagonal bipyramids, and edges with two equivalent Eu(4)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 26-44°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded to one Eu(2), one Eu(3), one Eu(4), and one Mn(3) atom to form OEu3Mn tetrahedra that share  a cornercorner with one O(1)Eu3Mn tetrahedra, corners with two equivalent O(9)Eu3Mn tetrahedra, corners with two equivalent O(12)Eu3Nb tetrahedra, corners with two equivalent O(8)Eu3Nb tetrahedra, corners with three equivalent O(7)Eu3Nb tetrahedra,  an edgeedge with one O(10)Eu3Mn tetrahedra,  an edgeedge with one O(11)Eu3Nb tetrahedra, and  an edgeedge with one O(2)Eu3Nb tetrahedra. In the second O site, O(2) is bonded to one Eu(1), one Eu(3), one Eu(4), and one Nb(3) atom to form distorted OEu3Nb tetrahedra that share  a cornercorner with one O(2)Eu3Nb tetrahedra, corners with two equivalent O(10)Eu3Mn tetrahedra, corners with two equivalent O(11)Eu3Nb tetrahedra, corners with two equivalent O(7)Eu3Nb tetrahedra, corners with three equivalent O(8)Eu3Nb tetrahedra,  a cornercorner with one O(3)EuMnNb2 trigonal pyramid,  an edgeedge with one O(1)Eu3Mn tetrahedra,  an edgeedge with one O(9)Eu3Mn tetrahedra,  an edgeedge with one O(12)Eu3Nb tetrahedra, and  an edgeedge with one O(3)EuMnNb2 trigonal pyramid. In the third O site, O(3) is bonded to one Eu(1), one Nb(1), one Nb(3), and one Mn(2) atom to form distorted OEuMnNb2 trigonal pyramids that share  a cornercorner with one O(10)Eu3Mn tetrahedra,  a cornercorner with one O(9)Eu3Mn tetrahedra,  a cornercorner with one O(12)Eu3Nb tetrahedra,  a cornercorner with one O(2)Eu3Nb tetrahedra,  a cornercorner with one O(7)Eu3Nb tetrahedra,  a cornercorner with one O(8)Eu3Nb tetrahedra,  an edgeedge with one O(10)Eu3Mn tetrahedra,  an edgeedge with one O(11)Eu3Nb tetrahedra,  an edgeedge with one O(2)Eu3Nb tetrahedra, and  an edgeedge with one O(3)EuMnNb2 trigonal pyramid. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Eu(2), one Nb(2), one Mn(1), and one Mn(3) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Eu(1) and two equivalent Nb(2) atoms. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Eu(2), two equivalent Nb(1), and one Mn(2) atom. In the seventh O site, O(7) is bonded to one Eu(2), one Eu(3), one Eu(4), and one Nb(1) atom to form distorted OEu3Nb tetrahedra that share corners with two equivalent O(10)Eu3Mn tetrahedra, corners with two equivalent O(2)Eu3Nb tetrahedra, corners with three equivalent O(1)Eu3Mn tetrahedra, corners with three equivalent O(11)Eu3Nb tetrahedra,  a cornercorner with one O(3)EuMnNb2 trigonal pyramid,  an edgeedge with one O(9)Eu3Mn tetrahedra,  an edgeedge with one O(12)Eu3Nb tetrahedra, and  an edgeedge with one O(8)Eu3Nb tetrahedra. In the eighth O site, O(8) is bonded to one Eu(1), one Eu(3), one Eu(4), and one Nb(2) atom to form distorted OEu3Nb tetrahedra that share corners with two equivalent O(1)Eu3Mn tetrahedra, corners with two equivalent O(9)Eu3Mn tetrahedra, corners with three equivalent O(12)Eu3Nb tetrahedra, corners with three equivalent O(2)Eu3Nb tetrahedra,  a cornercorner with one O(3)EuMnNb2 trigonal pyramid,  an edgeedge with one O(10)Eu3Mn tetrahedra,  an edgeedge with one O(11)Eu3Nb tetrahedra, and  an edgeedge with one O(7)Eu3Nb tetrahedra. In the ninth O site, O(9) is bonded to one Eu(1), one Eu(2), one Eu(4), and one Mn(1) atom to form OEu3Mn tetrahedra that share  a cornercorner with one O(9)Eu3Mn tetrahedra, corners with two equivalent O(1)Eu3Mn tetrahedra, corners with two equivalent O(12)Eu3Nb tetrahedra, corners with two equivalent O(8)Eu3Nb tetrahedra, corners with three equivalent O(11)Eu3Nb tetrahedra,  a cornercorner with one O(3)EuMnNb2 trigonal pyramid,  an edgeedge with one O(10)Eu3Mn tetrahedra,  an edgeedge with one O(2)Eu3Nb tetrahedra, and  an edgeedge with one O(7)Eu3Nb tetrahedra. In the tenth O site, O(10) is bonded to one Eu(1), one Eu(2), one Eu(3), and one Mn(2) atom to form OEu3Mn tetrahedra that share  a cornercorner with one O(10)Eu3Mn tetrahedra, corners with two equivalent O(11)Eu3Nb tetrahedra, corners with two equivalent O(2)Eu3Nb tetrahedra, corners with two equivalent O(7)Eu3Nb tetrahedra, corners with three equivalent O(12)Eu3Nb tetrahedra,  a cornercorner with one O(3)EuMnNb2 trigonal pyramid,  an edgeedge with one O(1)Eu3Mn tetrahedra,  an edgeedge with one O(9)Eu3Mn tetrahedra,  an edgeedge with one O(8)Eu3Nb tetrahedra, and  an edgeedge with one O(3)EuMnNb2 trigonal pyramid. In the eleventh O site, O(11) is bonded to one Eu(1), one Eu(2), one Eu(4), and one Nb(1) atom to form OEu3Nb tetrahedra that share corners with two equivalent O(10)Eu3Mn tetrahedra, corners with two equivalent O(2)Eu3Nb tetrahedra, corners with three equivalent O(9)Eu3Mn tetrahedra, corners with three equivalent O(7)Eu3Nb tetrahedra,  an edgeedge with one O(1)Eu3Mn tetrahedra,  an edgeedge with one O(12)Eu3Nb tetrahedra,  an edgeedge with one O(8)Eu3Nb tetrahedra, and  an edgeedge with one O(3)EuMnNb2 trigonal pyramid. In the twelfth O site, O(12) is bonded to one Eu(1), one Eu(2), one Eu(3), and one Nb(2) atom to form OEu3Nb tetrahedra that share corners with two equivalent O(1)Eu3Mn tetrahedra, corners with two equivalent O(9)Eu3Mn tetrahedra, corners with three equivalent O(10)Eu3Mn tetrahedra, corners with three equivalent O(8)Eu3Nb tetrahedra,  a cornercorner with one O(3)EuMnNb2 trigonal pyramid,  an edgeedge with one O(11)Eu3Nb tetrahedra,  an edgeedge with one O(2)Eu3Nb tetrahedra, and  an edgeedge with one O(7)Eu3Nb tetrahedra. In the thirteenth O site, O(13) is bonded in a distorted T-shaped geometry to one Eu(3), one Nb(1), and one Nb(3) atom. In the fourteenth O site, O(14) is bonded in a distorted T-shaped geometry to one Eu(4), one Nb(2), and one Mn(3) atom.
Eu8Nb5Mn3O28 crystallizes in the monoclinic C2 space group. There are four inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a distorted body-centered cubic geometry to one O(10), one O(11), one O(12), one O(2), one O(3), one O(5), one O(8), and one O(9) atom. The Eu(1)-O(10) bond length is 2.45 Å. The Eu(1)-O(11) bond length is 2.48 Å. The Eu(1)-O(12) bond length is 2.50 Å. The Eu(1)-O(2) bond length is 2.53 Å. The Eu(1)-O(3) bond length is 2.65 Å. The Eu(1)-O(5) bond length is 2.68 Å. The Eu(1)-O(8) bond length is 2.47 Å. The Eu(1)-O(9) bond length is 2.43 Å. In the second Eu site, Eu(2) is bonded in a distorted body-centered cubic geometry to one O(1), one O(10), one O(11), one O(12), one O(4), one O(6), one O(7), and one O(9) atom. The Eu(2)-O(1) bond length is 2.44 Å. The Eu(2)-O(10) bond length is 2.42 Å. The Eu(2)-O(11) bond length is 2.50 Å. The Eu(2)-O(12) bond length is 2.46 Å. The Eu(2)-O(4) bond length is 2.64 Å. The Eu(2)-O(6) bond length is 2.67 Å. The Eu(2)-O(7) bond length is 2.57 Å. The Eu(2)-O(9) bond length is 2.44 Å. In the third Eu site, Eu(3) is bonded to one O(1), one O(10), one O(12), one O(13), one O(2), one O(7), and one O(8) atom to form distorted EuO7 pentagonal bipyramids that share  a cornercorner with one Mn(3)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra,  an edgeedge with one Nb(3)O6 octahedra, and edges with two equivalent Eu(4)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 49-60°. The Eu(3)-O(1) bond length is 2.36 Å. The Eu(3)-O(10) bond length is 2.38 Å. The Eu(3)-O(12) bond length is 2.37 Å. The Eu(3)-O(13) bond length is 2.62 Å. The Eu(3)-O(2) bond length is 2.53 Å. The Eu(3)-O(7) bond length is 2.57 Å. The Eu(3)-O(8) bond length is 2.38 Å. In the fourth Eu site, Eu(4) is bonded to one O(1), one O(11), one O(14), one O(2), one O(7), one O(8), and one O(9) atom to form distorted EuO7 pentagonal bipyramids that share  a cornercorner with one Nb(3)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra,  an edgeedge with one Mn(3)O6 octahedra, and edges with two equivalent Eu(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 48-51°. The Eu(4)-O(1) bond length is 2.45 Å. The Eu(4)-O(11) bond length is 2.38 Å. The Eu(4)-O(14) bond length is 2.53 Å. The Eu(4)-O(2) bond length is 2.37 Å. The Eu(4)-O(7) bond length is 2.46 Å. The Eu(4)-O(8) bond length is 2.52 Å. The Eu(4)-O(9) bond length is 2.44 Å. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(11), one O(13), one O(3), one O(7), and two equivalent O(6) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra, corners with two equivalent Eu(4)O7 pentagonal bipyramids, and  an edgeedge with one Eu(3)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 24-49°. The Nb(1)-O(11) bond length is 2.05 Å. The Nb(1)-O(13) bond length is 2.03 Å. The Nb(1)-O(3) bond length is 2.04 Å. The Nb(1)-O(7) bond length is 1.97 Å. There is one shorter (1.91 Å) and one longer (2.19 Å) Nb(1)-O(6) bond length. In the second Nb site, Nb(2) is bonded to one O(12), one O(14), one O(4), one O(8), and two equivalent O(5) atoms to form NbO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Eu(3)O7 pentagonal bipyramids, and  an edgeedge with one Eu(4)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 26-44°. The Nb(2)-O(12) bond length is 2.03 Å. The Nb(2)-O(14) bond length is 1.95 Å. The Nb(2)-O(4) bond length is 2.17 Å. The Nb(2)-O(8) bond length is 1.99 Å. There is one shorter (1.95 Å) and one longer (2.16 Å) Nb(2)-O(5) bond length. In the third Nb site, Nb(3) is bonded to two equivalent O(13), two equivalent O(2), and two equivalent O(3) atoms to form NbO6 octahedra that share corners with four equivalent Nb(1)O6 octahedra, corners with two equivalent Eu(4)O7 pentagonal bipyramids, and edges with two equivalent Eu(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 24-49°. Both Nb(3)-O(13) bond lengths are 1.97 Å. Both Nb(3)-O(2) bond lengths are 1.99 Å. Both Nb(3)-O(3) bond lengths are 2.12 Å. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 4-coordinate geometry to two equivalent O(4) and two equivalent O(9) atoms. Both Mn(1)-O(4) bond lengths are 2.10 Å. Both Mn(1)-O(9) bond lengths are 1.89 Å. In the second Mn site, Mn(2) is bonded in a 4-coordinate geometry to two equivalent O(10), two equivalent O(3), and two equivalent O(6) atoms. Both Mn(2)-O(10) bond lengths are 1.92 Å. Both Mn(2)-O(3) bond lengths are 2.16 Å. Both Mn(2)-O(6) bond lengths are 2.79 Å. In the third Mn site, Mn(3) is bonded to two equivalent O(1), two equivalent O(14), and two equivalent O(4) atoms to form MnO6 octahedra that share corners with four equivalent Nb(2)O6 octahedra, corners with two equivalent Eu(3)O7 pentagonal bipyramids, and edges with two equivalent Eu(4)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 26-44°. Both Mn(3)-O(1) bond lengths are 1.94 Å. Both Mn(3)-O(14) bond lengths are 2.00 Å. Both Mn(3)-O(4) bond lengths are 1.99 Å. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded to one Eu(2), one Eu(3), one Eu(4), and one Mn(3) atom to form OEu3Mn tetrahedra that share  a cornercorner with one O(1)Eu3Mn tetrahedra, corners with two equivalent O(9)Eu3Mn tetrahedra, corners with two equivalent O(12)Eu3Nb tetrahedra, corners with two equivalent O(8)Eu3Nb tetrahedra, corners with three equivalent O(7)Eu3Nb tetrahedra,  an edgeedge with one O(10)Eu3Mn tetrahedra,  an edgeedge with one O(11)Eu3Nb tetrahedra, and  an edgeedge with one O(2)Eu3Nb tetrahedra. In the second O site, O(2) is bonded to one Eu(1), one Eu(3), one Eu(4), and one Nb(3) atom to form distorted OEu3Nb tetrahedra that share  a cornercorner with one O(2)Eu3Nb tetrahedra, corners with two equivalent O(10)Eu3Mn tetrahedra, corners with two equivalent O(11)Eu3Nb tetrahedra, corners with two equivalent O(7)Eu3Nb tetrahedra, corners with three equivalent O(8)Eu3Nb tetrahedra,  a cornercorner with one O(3)EuMnNb2 trigonal pyramid,  an edgeedge with one O(1)Eu3Mn tetrahedra,  an edgeedge with one O(9)Eu3Mn tetrahedra,  an edgeedge with one O(12)Eu3Nb tetrahedra, and  an edgeedge with one O(3)EuMnNb2 trigonal pyramid. In the third O site, O(3) is bonded to one Eu(1), one Nb(1), one Nb(3), and one Mn(2) atom to form distorted OEuMnNb2 trigonal pyramids that share  a cornercorner with one O(10)Eu3Mn tetrahedra,  a cornercorner with one O(9)Eu3Mn tetrahedra,  a cornercorner with one O(12)Eu3Nb tetrahedra,  a cornercorner with one O(2)Eu3Nb tetrahedra,  a cornercorner with one O(7)Eu3Nb tetrahedra,  a cornercorner with one O(8)Eu3Nb tetrahedra,  an edgeedge with one O(10)Eu3Mn tetrahedra,  an edgeedge with one O(11)Eu3Nb tetrahedra,  an edgeedge with one O(2)Eu3Nb tetrahedra, and  an edgeedge with one O(3)EuMnNb2 trigonal pyramid. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Eu(2), one Nb(2), one Mn(1), and one Mn(3) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Eu(1) and two equivalent Nb(2) atoms. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Eu(2), two equivalent Nb(1), and one Mn(2) atom. In the seventh O site, O(7) is bonded to one Eu(2), one Eu(3), one Eu(4), and one Nb(1) atom to form distorted OEu3Nb tetrahedra that share corners with two equivalent O(10)Eu3Mn tetrahedra, corners with two equivalent O(2)Eu3Nb tetrahedra, corners with three equivalent O(1)Eu3Mn tetrahedra, corners with three equivalent O(11)Eu3Nb tetrahedra,  a cornercorner with one O(3)EuMnNb2 trigonal pyramid,  an edgeedge with one O(9)Eu3Mn tetrahedra,  an edgeedge with one O(12)Eu3Nb tetrahedra, and  an edgeedge with one O(8)Eu3Nb tetrahedra. In the eighth O site, O(8) is bonded to one Eu(1), one Eu(3), one Eu(4), and one Nb(2) atom to form distorted OEu3Nb tetrahedra that share corners with two equivalent O(1)Eu3Mn tetrahedra, corners with two equivalent O(9)Eu3Mn tetrahedra, corners with three equivalent O(12)Eu3Nb tetrahedra, corners with three equivalent O(2)Eu3Nb tetrahedra,  a cornercorner with one O(3)EuMnNb2 trigonal pyramid,  an edgeedge with one O(10)Eu3Mn tetrahedra,  an edgeedge with one O(11)Eu3Nb tetrahedra, and  an edgeedge with one O(7)Eu3Nb tetrahedra. In the ninth O site, O(9) is bonded to one Eu(1), one Eu(2), one Eu(4), and one Mn(1) atom to form OEu3Mn tetrahedra that share  a cornercorner with one O(9)Eu3Mn tetrahedra, corners with two equivalent O(1)Eu3Mn tetrahedra, corners with two equivalent O(12)Eu3Nb tetrahedra, corners with two equivalent O(8)Eu3Nb tetrahedra, corners with three equivalent O(11)Eu3Nb tetrahedra,  a cornercorner with one O(3)EuMnNb2 trigonal pyramid,  an edgeedge with one O(10)Eu3Mn tetrahedra,  an edgeedge with one O(2)Eu3Nb tetrahedra, and  an edgeedge with one O(7)Eu3Nb tetrahedra. In the tenth O site, O(10) is bonded to one Eu(1), one Eu(2), one Eu(3), and one Mn(2) atom to form OEu3Mn tetrahedra that share  a cornercorner with one O(10)Eu3Mn tetrahedra, corners with two equivalent O(11)Eu3Nb tetrahedra, corners with two equivalent O(2)Eu3Nb tetrahedra, corners with two equivalent O(7)Eu3Nb tetrahedra, corners with three equivalent O(12)Eu3Nb tetrahedra,  a cornercorner with one O(3)EuMnNb2 trigonal pyramid,  an edgeedge with one O(1)Eu3Mn tetrahedra,  an edgeedge with one O(9)Eu3Mn tetrahedra,  an edgeedge with one O(8)Eu3Nb tetrahedra, and  an edgeedge with one O(3)EuMnNb2 trigonal pyramid. In the eleventh O site, O(11) is bonded to one Eu(1), one Eu(2), one Eu(4), and one Nb(1) atom to form OEu3Nb tetrahedra that share corners with two equivalent O(10)Eu3Mn tetrahedra, corners with two equivalent O(2)Eu3Nb tetrahedra, corners with three equivalent O(9)Eu3Mn tetrahedra, corners with three equivalent O(7)Eu3Nb tetrahedra,  an edgeedge with one O(1)Eu3Mn tetrahedra,  an edgeedge with one O(12)Eu3Nb tetrahedra,  an edgeedge with one O(8)Eu3Nb tetrahedra, and  an edgeedge with one O(3)EuMnNb2 trigonal pyramid. In the twelfth O site, O(12) is bonded to one Eu(1), one Eu(2), one Eu(3), and one Nb(2) atom to form OEu3Nb tetrahedra that share corners with two equivalent O(1)Eu3Mn tetrahedra, corners with two equivalent O(9)Eu3Mn tetrahedra, corners with three equivalent O(10)Eu3Mn tetrahedra, corners with three equivalent O(8)Eu3Nb tetrahedra,  a cornercorner with one O(3)EuMnNb2 trigonal pyramid,  an edgeedge with one O(11)Eu3Nb tetrahedra,  an edgeedge with one O(2)Eu3Nb tetrahedra, and  an edgeedge with one O(7)Eu3Nb tetrahedra. In the thirteenth O site, O(13) is bonded in a distorted T-shaped geometry to one Eu(3), one Nb(1), and one Nb(3) atom. In the fourteenth O site, O(14) is bonded in a distorted T-shaped geometry to one Eu(4), one Nb(2), and one Mn(3) atom.