MgTm4Ti2O10 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(3), one O(4), one O(6), one O(7), and one O(8) atom to form distorted MgO5 square pyramids that share  a cornercorner with one Tm(2)O6 octahedra, corners with two equivalent Tm(1)O6 octahedra,  a cornercorner with one Ti(1)O5 square pyramid,  an edgeedge with one Tm(1)O6 octahedra,  an edgeedge with one Ti(2)O6 octahedra, and  an edgeedge with one Ti(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 43-83°. There are four inequivalent Tm sites. In the first Tm site, Tm(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(7), and one O(8) atom to form distorted TmO6 octahedra that share corners with two equivalent Tm(2)O6 octahedra, corners with three equivalent Ti(2)O6 octahedra,  a cornercorner with one Ti(1)O5 square pyramid, corners with two equivalent Mg(1)O5 square pyramids,  an edgeedge with one Mg(1)O5 square pyramid, and  an edgeedge with one Ti(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 36-62°. In the second Tm site, Tm(2) is bonded to one O(1), one O(10), one O(2), one O(5), one O(6), and one O(9) atom to form distorted TmO6 octahedra that share corners with two equivalent Tm(1)O6 octahedra,  a cornercorner with one Mg(1)O5 square pyramid, corners with three equivalent Ti(1)O5 square pyramids, and edges with two equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-62°. In the third Tm site, Tm(3) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(7), one O(8), and one O(9) atom. In the fourth Tm site, Tm(4) is bonded in a 6-coordinate geometry to one O(10), one O(2), one O(5), one O(6), one O(7), and one O(9) atom. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(10), one O(2), one O(3), one O(6), and one O(7) atom to form distorted TiO5 square pyramids that share  a cornercorner with one Tm(1)O6 octahedra,  a cornercorner with one Ti(2)O6 octahedra, corners with three equivalent Tm(2)O6 octahedra,  a cornercorner with one Mg(1)O5 square pyramid,  an edgeedge with one Tm(1)O6 octahedra, and  an edgeedge with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 41-68°. In the second Ti site, Ti(2) is bonded to one O(1), one O(10), one O(4), one O(5), one O(8), and one O(9) atom to form TiO6 octahedra that share corners with three equivalent Tm(1)O6 octahedra,  a cornercorner with one Ti(1)O5 square pyramid, edges with two equivalent Tm(2)O6 octahedra, and  an edgeedge with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 36-51°. There are ten inequivalent O sites. In the first O site, O(1) is bonded to one Tm(1), one Tm(2), one Tm(3), and one Ti(2) atom to form OTm3Ti trigonal pyramids that share  a cornercorner with one O(4)Tm2MgTi trigonal pyramid,  a cornercorner with one O(9)Tm3Ti trigonal pyramid, corners with two equivalent O(2)Tm3Ti trigonal pyramids,  an edgeedge with one O(7)Tm3MgTi trigonal bipyramid,  an edgeedge with one O(4)Tm2MgTi trigonal pyramid,  an edgeedge with one O(10)Tm2Ti2 trigonal pyramid, and  an edgeedge with one O(9)Tm3Ti trigonal pyramid. In the second O site, O(2) is bonded to one Tm(1), one Tm(2), one Tm(4), and one Ti(1) atom to form distorted OTm3Ti trigonal pyramids that share  a cornercorner with one O(7)Tm3MgTi trigonal bipyramid,  a cornercorner with one O(4)Tm2MgTi trigonal pyramid,  a cornercorner with one O(10)Tm2Ti2 trigonal pyramid, corners with two equivalent O(1)Tm3Ti trigonal pyramids,  an edgeedge with one O(7)Tm3MgTi trigonal bipyramid,  an edgeedge with one O(10)Tm2Ti2 trigonal pyramid, and  an edgeedge with one O(9)Tm3Ti trigonal pyramid. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to one Mg(1), one Tm(1), one Tm(3), and one Ti(1) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Tm(1), one Tm(3), and one Ti(2) atom to form OTm2MgTi trigonal pyramids that share  a cornercorner with one O(7)Tm3MgTi trigonal bipyramid,  a cornercorner with one O(10)Tm2Ti2 trigonal pyramid,  a cornercorner with one O(1)Tm3Ti trigonal pyramid,  a cornercorner with one O(2)Tm3Ti trigonal pyramid, corners with two equivalent O(9)Tm3Ti trigonal pyramids,  an edgeedge with one O(7)Tm3MgTi trigonal bipyramid, and  an edgeedge with one O(1)Tm3Ti trigonal pyramid. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Tm(2), one Tm(4), and one Ti(2) atom. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Mg(1), one Tm(2), one Tm(4), and one Ti(1) atom. In the seventh O site, O(7) is bonded to one Mg(1), one Tm(1), one Tm(3), one Tm(4), and one Ti(1) atom to form distorted OTm3MgTi trigonal bipyramids that share  a cornercorner with one O(4)Tm2MgTi trigonal pyramid,  a cornercorner with one O(2)Tm3Ti trigonal pyramid, corners with two equivalent O(9)Tm3Ti trigonal pyramids,  an edgeedge with one O(4)Tm2MgTi trigonal pyramid,  an edgeedge with one O(10)Tm2Ti2 trigonal pyramid,  an edgeedge with one O(1)Tm3Ti trigonal pyramid, and  an edgeedge with one O(2)Tm3Ti trigonal pyramid. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Tm(1), one Tm(3), and one Ti(2) atom. In the ninth O site, O(9) is bonded to one Tm(2), one Tm(3), one Tm(4), and one Ti(2) atom to form OTm3Ti trigonal pyramids that share corners with two equivalent O(7)Tm3MgTi trigonal bipyramids,  a cornercorner with one O(10)Tm2Ti2 trigonal pyramid,  a cornercorner with one O(1)Tm3Ti trigonal pyramid, corners with two equivalent O(4)Tm2MgTi trigonal pyramids,  an edgeedge with one O(10)Tm2Ti2 trigonal pyramid,  an edgeedge with one O(1)Tm3Ti trigonal pyramid, and  an edgeedge with one O(2)Tm3Ti trigonal pyramid. In the tenth O site, O(10) is bonded to one Tm(2), one Tm(4), one Ti(1), and one Ti(2) atom to form distorted OTm2Ti2 trigonal pyramids that share  a cornercorner with one O(4)Tm2MgTi trigonal pyramid,  a cornercorner with one O(2)Tm3Ti trigonal pyramid,  a cornercorner with one O(9)Tm3Ti trigonal pyramid,  an edgeedge with one O(7)Tm3MgTi trigonal bipyramid,  an edgeedge with one O(1)Tm3Ti trigonal pyramid,  an edgeedge with one O(2)Tm3Ti trigonal pyramid, and  an edgeedge with one O(9)Tm3Ti trigonal pyramid.
MgTm4Ti2O10 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(3), one O(4), one O(6), one O(7), and one O(8) atom to form distorted MgO5 square pyramids that share  a cornercorner with one Tm(2)O6 octahedra, corners with two equivalent Tm(1)O6 octahedra,  a cornercorner with one Ti(1)O5 square pyramid,  an edgeedge with one Tm(1)O6 octahedra,  an edgeedge with one Ti(2)O6 octahedra, and  an edgeedge with one Ti(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 43-83°. The Mg(1)-O(3) bond length is 2.28 Å. The Mg(1)-O(4) bond length is 2.03 Å. The Mg(1)-O(6) bond length is 1.98 Å. The Mg(1)-O(7) bond length is 2.13 Å. The Mg(1)-O(8) bond length is 1.98 Å. There are four inequivalent Tm sites. In the first Tm site, Tm(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(7), and one O(8) atom to form distorted TmO6 octahedra that share corners with two equivalent Tm(2)O6 octahedra, corners with three equivalent Ti(2)O6 octahedra,  a cornercorner with one Ti(1)O5 square pyramid, corners with two equivalent Mg(1)O5 square pyramids,  an edgeedge with one Mg(1)O5 square pyramid, and  an edgeedge with one Ti(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 36-62°. The Tm(1)-O(1) bond length is 2.19 Å. The Tm(1)-O(2) bond length is 2.31 Å. The Tm(1)-O(3) bond length is 2.24 Å. The Tm(1)-O(4) bond length is 2.18 Å. The Tm(1)-O(7) bond length is 2.31 Å. The Tm(1)-O(8) bond length is 2.22 Å. In the second Tm site, Tm(2) is bonded to one O(1), one O(10), one O(2), one O(5), one O(6), and one O(9) atom to form distorted TmO6 octahedra that share corners with two equivalent Tm(1)O6 octahedra,  a cornercorner with one Mg(1)O5 square pyramid, corners with three equivalent Ti(1)O5 square pyramids, and edges with two equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-62°. The Tm(2)-O(1) bond length is 2.18 Å. The Tm(2)-O(10) bond length is 2.27 Å. The Tm(2)-O(2) bond length is 2.34 Å. The Tm(2)-O(5) bond length is 2.18 Å. The Tm(2)-O(6) bond length is 2.19 Å. The Tm(2)-O(9) bond length is 2.36 Å. In the third Tm site, Tm(3) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(7), one O(8), and one O(9) atom. The Tm(3)-O(1) bond length is 2.34 Å. The Tm(3)-O(3) bond length is 2.19 Å. The Tm(3)-O(4) bond length is 2.16 Å. The Tm(3)-O(7) bond length is 2.56 Å. The Tm(3)-O(8) bond length is 2.25 Å. The Tm(3)-O(9) bond length is 2.14 Å. In the fourth Tm site, Tm(4) is bonded in a 6-coordinate geometry to one O(10), one O(2), one O(5), one O(6), one O(7), and one O(9) atom. The Tm(4)-O(10) bond length is 2.32 Å. The Tm(4)-O(2) bond length is 2.49 Å. The Tm(4)-O(5) bond length is 2.15 Å. The Tm(4)-O(6) bond length is 2.16 Å. The Tm(4)-O(7) bond length is 2.30 Å. The Tm(4)-O(9) bond length is 2.24 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(10), one O(2), one O(3), one O(6), and one O(7) atom to form distorted TiO5 square pyramids that share  a cornercorner with one Tm(1)O6 octahedra,  a cornercorner with one Ti(2)O6 octahedra, corners with three equivalent Tm(2)O6 octahedra,  a cornercorner with one Mg(1)O5 square pyramid,  an edgeedge with one Tm(1)O6 octahedra, and  an edgeedge with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 41-68°. The Ti(1)-O(10) bond length is 1.94 Å. The Ti(1)-O(2) bond length is 1.97 Å. The Ti(1)-O(3) bond length is 2.05 Å. The Ti(1)-O(6) bond length is 2.24 Å. The Ti(1)-O(7) bond length is 2.18 Å. In the second Ti site, Ti(2) is bonded to one O(1), one O(10), one O(4), one O(5), one O(8), and one O(9) atom to form TiO6 octahedra that share corners with three equivalent Tm(1)O6 octahedra,  a cornercorner with one Ti(1)O5 square pyramid, edges with two equivalent Tm(2)O6 octahedra, and  an edgeedge with one Mg(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 36-51°. The Ti(2)-O(1) bond length is 2.11 Å. The Ti(2)-O(10) bond length is 2.09 Å. The Ti(2)-O(4) bond length is 2.13 Å. The Ti(2)-O(5) bond length is 1.95 Å. The Ti(2)-O(8) bond length is 2.19 Å. The Ti(2)-O(9) bond length is 2.11 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded to one Tm(1), one Tm(2), one Tm(3), and one Ti(2) atom to form OTm3Ti trigonal pyramids that share  a cornercorner with one O(4)Tm2MgTi trigonal pyramid,  a cornercorner with one O(9)Tm3Ti trigonal pyramid, corners with two equivalent O(2)Tm3Ti trigonal pyramids,  an edgeedge with one O(7)Tm3MgTi trigonal bipyramid,  an edgeedge with one O(4)Tm2MgTi trigonal pyramid,  an edgeedge with one O(10)Tm2Ti2 trigonal pyramid, and  an edgeedge with one O(9)Tm3Ti trigonal pyramid. In the second O site, O(2) is bonded to one Tm(1), one Tm(2), one Tm(4), and one Ti(1) atom to form distorted OTm3Ti trigonal pyramids that share  a cornercorner with one O(7)Tm3MgTi trigonal bipyramid,  a cornercorner with one O(4)Tm2MgTi trigonal pyramid,  a cornercorner with one O(10)Tm2Ti2 trigonal pyramid, corners with two equivalent O(1)Tm3Ti trigonal pyramids,  an edgeedge with one O(7)Tm3MgTi trigonal bipyramid,  an edgeedge with one O(10)Tm2Ti2 trigonal pyramid, and  an edgeedge with one O(9)Tm3Ti trigonal pyramid. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to one Mg(1), one Tm(1), one Tm(3), and one Ti(1) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Tm(1), one Tm(3), and one Ti(2) atom to form OTm2MgTi trigonal pyramids that share  a cornercorner with one O(7)Tm3MgTi trigonal bipyramid,  a cornercorner with one O(10)Tm2Ti2 trigonal pyramid,  a cornercorner with one O(1)Tm3Ti trigonal pyramid,  a cornercorner with one O(2)Tm3Ti trigonal pyramid, corners with two equivalent O(9)Tm3Ti trigonal pyramids,  an edgeedge with one O(7)Tm3MgTi trigonal bipyramid, and  an edgeedge with one O(1)Tm3Ti trigonal pyramid. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Tm(2), one Tm(4), and one Ti(2) atom. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Mg(1), one Tm(2), one Tm(4), and one Ti(1) atom. In the seventh O site, O(7) is bonded to one Mg(1), one Tm(1), one Tm(3), one Tm(4), and one Ti(1) atom to form distorted OTm3MgTi trigonal bipyramids that share  a cornercorner with one O(4)Tm2MgTi trigonal pyramid,  a cornercorner with one O(2)Tm3Ti trigonal pyramid, corners with two equivalent O(9)Tm3Ti trigonal pyramids,  an edgeedge with one O(4)Tm2MgTi trigonal pyramid,  an edgeedge with one O(10)Tm2Ti2 trigonal pyramid,  an edgeedge with one O(1)Tm3Ti trigonal pyramid, and  an edgeedge with one O(2)Tm3Ti trigonal pyramid. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Tm(1), one Tm(3), and one Ti(2) atom. In the ninth O site, O(9) is bonded to one Tm(2), one Tm(3), one Tm(4), and one Ti(2) atom to form OTm3Ti trigonal pyramids that share corners with two equivalent O(7)Tm3MgTi trigonal bipyramids,  a cornercorner with one O(10)Tm2Ti2 trigonal pyramid,  a cornercorner with one O(1)Tm3Ti trigonal pyramid, corners with two equivalent O(4)Tm2MgTi trigonal pyramids,  an edgeedge with one O(10)Tm2Ti2 trigonal pyramid,  an edgeedge with one O(1)Tm3Ti trigonal pyramid, and  an edgeedge with one O(2)Tm3Ti trigonal pyramid. In the tenth O site, O(10) is bonded to one Tm(2), one Tm(4), one Ti(1), and one Ti(2) atom to form distorted OTm2Ti2 trigonal pyramids that share  a cornercorner with one O(4)Tm2MgTi trigonal pyramid,  a cornercorner with one O(2)Tm3Ti trigonal pyramid,  a cornercorner with one O(9)Tm3Ti trigonal pyramid,  an edgeedge with one O(7)Tm3MgTi trigonal bipyramid,  an edgeedge with one O(1)Tm3Ti trigonal pyramid,  an edgeedge with one O(2)Tm3Ti trigonal pyramid, and  an edgeedge with one O(9)Tm3Ti trigonal pyramid.