MgYb4Ti2O10 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form distorted MgO6 octahedra that share corners with four equivalent Ti(1)O5 trigonal bipyramids and edges with two equivalent Mg(1)O6 octahedra. There are two inequivalent Yb sites. In the first Yb site, Yb(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(5), and three equivalent O(3) atoms. In the second Yb site, Yb(2) is bonded in a 6-coordinate geometry to one O(5), two equivalent O(1), and three equivalent O(4) atoms. Ti(1) is bonded to one O(1), one O(2), one O(4), and two equivalent O(5) atoms to form distorted TiO5 trigonal bipyramids that share corners with two equivalent Mg(1)O6 octahedra and corners with two equivalent Ti(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 71°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Yb(1), two equivalent Yb(2), and one Ti(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Mg(1), one Yb(1), one Ti(1), and one O(2) atom. In the third O site, O(3) is bonded to one Mg(1) and three equivalent Yb(1) atoms to form OYb3Mg tetrahedra that share corners with three equivalent O(3)Yb3Mg tetrahedra, corners with three equivalent O(5)Yb2Ti2 trigonal pyramids, and edges with two equivalent O(3)Yb3Mg tetrahedra. In the fourth O site, O(4) is bonded to three equivalent Yb(2) and one Ti(1) atom to form distorted OYb3Ti trigonal pyramids that share  a cornercorner with one O(5)Yb2Ti2 trigonal pyramid, corners with two equivalent O(4)Yb3Ti trigonal pyramids, edges with two equivalent O(5)Yb2Ti2 trigonal pyramids, and edges with two equivalent O(4)Yb3Ti trigonal pyramids. In the fifth O site, O(5) is bonded to one Yb(1), one Yb(2), and two equivalent Ti(1) atoms to form distorted OYb2Ti2 trigonal pyramids that share corners with three equivalent O(3)Yb3Mg tetrahedra,  a cornercorner with one O(4)Yb3Ti trigonal pyramid, corners with two equivalent O(5)Yb2Ti2 trigonal pyramids, and edges with two equivalent O(4)Yb3Ti trigonal pyramids.
MgYb4Ti2O10 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form distorted MgO6 octahedra that share corners with four equivalent Ti(1)O5 trigonal bipyramids and edges with two equivalent Mg(1)O6 octahedra. Both Mg(1)-O(3) bond lengths are 1.96 Å. All Mg(1)-O(2) bond lengths are 2.17 Å. There are two inequivalent Yb sites. In the first Yb site, Yb(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(5), and three equivalent O(3) atoms. The Yb(1)-O(1) bond length is 2.80 Å. The Yb(1)-O(2) bond length is 2.45 Å. The Yb(1)-O(5) bond length is 2.39 Å. There are two shorter (2.18 Å) and one longer (2.20 Å) Yb(1)-O(3) bond length. In the second Yb site, Yb(2) is bonded in a 6-coordinate geometry to one O(5), two equivalent O(1), and three equivalent O(4) atoms. The Yb(2)-O(5) bond length is 2.40 Å. There is one shorter (2.32 Å) and one longer (2.43 Å) Yb(2)-O(1) bond length. There are two shorter (2.20 Å) and one longer (2.34 Å) Yb(2)-O(4) bond length. Ti(1) is bonded to one O(1), one O(2), one O(4), and two equivalent O(5) atoms to form distorted TiO5 trigonal bipyramids that share corners with two equivalent Mg(1)O6 octahedra and corners with two equivalent Ti(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 71°. The Ti(1)-O(1) bond length is 1.78 Å. The Ti(1)-O(2) bond length is 2.07 Å. The Ti(1)-O(4) bond length is 1.82 Å. Both Ti(1)-O(5) bond lengths are 2.10 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Yb(1), two equivalent Yb(2), and one Ti(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Mg(1), one Yb(1), one Ti(1), and one O(2) atom. The O(2)-O(2) bond length is 1.48 Å. In the third O site, O(3) is bonded to one Mg(1) and three equivalent Yb(1) atoms to form OYb3Mg tetrahedra that share corners with three equivalent O(3)Yb3Mg tetrahedra, corners with three equivalent O(5)Yb2Ti2 trigonal pyramids, and edges with two equivalent O(3)Yb3Mg tetrahedra. In the fourth O site, O(4) is bonded to three equivalent Yb(2) and one Ti(1) atom to form distorted OYb3Ti trigonal pyramids that share  a cornercorner with one O(5)Yb2Ti2 trigonal pyramid, corners with two equivalent O(4)Yb3Ti trigonal pyramids, edges with two equivalent O(5)Yb2Ti2 trigonal pyramids, and edges with two equivalent O(4)Yb3Ti trigonal pyramids. In the fifth O site, O(5) is bonded to one Yb(1), one Yb(2), and two equivalent Ti(1) atoms to form distorted OYb2Ti2 trigonal pyramids that share corners with three equivalent O(3)Yb3Mg tetrahedra,  a cornercorner with one O(4)Yb3Ti trigonal pyramid, corners with two equivalent O(5)Yb2Ti2 trigonal pyramids, and edges with two equivalent O(4)Yb3Ti trigonal pyramids.