MgSm8Ti4O20 crystallizes in the monoclinic Pm space group. Mg(1) is bonded in a 6-coordinate geometry to one O(10), one O(9), two equivalent O(13), and two equivalent O(6) atoms. There are eight inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 7-coordinate geometry to one O(15), one O(17), one O(8), two equivalent O(1), and two equivalent O(4) atoms. In the second Sm site, Sm(2) is bonded in a 8-coordinate geometry to one O(10), one O(20), two equivalent O(16), two equivalent O(3), and two equivalent O(6) atoms. In the third Sm site, Sm(3) is bonded to one O(1), one O(11), two equivalent O(5), and two equivalent O(8) atoms to form distorted SmO6 octahedra that share corners with two equivalent Sm(7)O6 octahedra, corners with two equivalent Ti(3)O6 octahedra, corners with two equivalent Sm(5)O7 pentagonal bipyramids, corners with two equivalent Ti(1)O5 trigonal bipyramids, and edges with two equivalent Sm(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-68°. In the fourth Sm site, Sm(4) is bonded in a 7-coordinate geometry to one O(14), one O(2), one O(3), two equivalent O(10), and two equivalent O(7) atoms. In the fifth Sm site, Sm(5) is bonded to one O(18), one O(19), one O(7), two equivalent O(11), and two equivalent O(14) atoms to form distorted SmO7 pentagonal bipyramids that share corners with two equivalent Sm(3)O6 octahedra, corners with two equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Sm(7)O6 octahedra, and edges with two equivalent Sm(5)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 59°. In the sixth Sm site, Sm(6) is bonded in a 9-coordinate geometry to one O(10), one O(19), one O(20), two equivalent O(13), two equivalent O(14), and two equivalent O(16) atoms. In the seventh Sm site, Sm(7) is bonded to one O(1), one O(11), two equivalent O(15), and two equivalent O(18) atoms to form SmO6 octahedra that share corners with two equivalent Sm(3)O6 octahedra, corners with two equivalent Ti(3)O6 octahedra, corners with two equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Sm(7)O6 octahedra, and edges with two equivalent Sm(5)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 51-68°. In the eighth Sm site, Sm(8) is bonded to one O(13), one O(4), two equivalent O(17), and two equivalent O(20) atoms to form distorted SmO6 octahedra that share corners with two equivalent Ti(3)O6 octahedra,  a cornercorner with one Ti(2)O5 trigonal bipyramid, and edges with two equivalent Sm(8)O6 octahedra. The corner-sharing octahedral tilt angles are 61°. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(18), one O(5), one O(7), and two equivalent O(2) atoms to form TiO5 trigonal bipyramids that share corners with two equivalent Sm(3)O6 octahedra, corners with two equivalent Sm(7)O6 octahedra, corners with two equivalent Sm(5)O7 pentagonal bipyramids, and corners with two equivalent Ti(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 50-68°. In the second Ti site, Ti(2) is bonded to one O(12), one O(4), one O(6), and two equivalent O(9) atoms to form distorted TiO5 trigonal bipyramids that share  a cornercorner with one Sm(8)O6 octahedra, corners with two equivalent Ti(2)O5 trigonal bipyramids, and edges with two equivalent Ti(3)O6 octahedra. The corner-sharing octahedral tilt angles are 58°. In the third Ti site, Ti(3) is bonded to one O(15), one O(17), one O(8), one O(9), and two equivalent O(12) atoms to form distorted TiO6 octahedra that share corners with two equivalent Sm(3)O6 octahedra, corners with two equivalent Sm(7)O6 octahedra, corners with two equivalent Sm(8)O6 octahedra, corners with two equivalent Ti(3)O6 octahedra, and edges with two equivalent Ti(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 38-65°. In the fourth Ti site, Ti(4) is bonded in a 6-coordinate geometry to one O(14), one O(16), one O(2), one O(3), and two equivalent O(19) atoms. There are twenty inequivalent O sites. In the first O site, O(1) is bonded to one Sm(3), one Sm(7), and two equivalent Sm(1) atoms to form OSm4 tetrahedra that share corners with two equivalent O(17)Sm3Ti tetrahedra, corners with two equivalent O(18)Sm3Ti tetrahedra, corners with two equivalent O(1)Sm4 tetrahedra, corners with two equivalent O(11)Sm4 tetrahedra, and edges with two equivalent O(8)Sm3Ti trigonal pyramids. In the second O site, O(2) is bonded to one Sm(4), one Ti(4), and two equivalent Ti(1) atoms to form distorted OSmTi3 trigonal pyramids that share corners with two equivalent O(18)Sm3Ti tetrahedra, corners with two equivalent O(2)SmTi3 trigonal pyramids,  an edgeedge with one O(3)Sm3Ti tetrahedra, and edges with two equivalent O(7)Sm3Ti tetrahedra. In the third O site, O(3) is bonded to one Sm(4), two equivalent Sm(2), and one Ti(4) atom to form OSm3Ti tetrahedra that share corners with two equivalent O(3)Sm3Ti tetrahedra, corners with two equivalent O(7)Sm3Ti tetrahedra, corners with two equivalent O(20)Sm4 tetrahedra, and  an edgeedge with one O(2)SmTi3 trigonal pyramid. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Sm(8), two equivalent Sm(1), and one Ti(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Sm(3) and one Ti(1) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to two equivalent Mg(1), two equivalent Sm(2), and one Ti(2) atom. In the seventh O site, O(7) is bonded to one Sm(5), two equivalent Sm(4), and one Ti(1) atom to form OSm3Ti tetrahedra that share corners with two equivalent O(18)Sm3Ti tetrahedra, corners with two equivalent O(3)Sm3Ti tetrahedra, corners with two equivalent O(7)Sm3Ti tetrahedra, corners with two equivalent O(11)Sm4 tetrahedra, and edges with two equivalent O(2)SmTi3 trigonal pyramids. In the eighth O site, O(8) is bonded to one Sm(1), two equivalent Sm(3), and one Ti(3) atom to form distorted OSm3Ti trigonal pyramids that share corners with two equivalent O(17)Sm3Ti tetrahedra, corners with two equivalent O(11)Sm4 tetrahedra, corners with two equivalent O(8)Sm3Ti trigonal pyramids, and edges with two equivalent O(1)Sm4 tetrahedra. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Mg(1), one Ti(3), and two equivalent Ti(2) atoms. In the tenth O site, O(10) is bonded in a 5-coordinate geometry to one Mg(1), one Sm(2), one Sm(6), and two equivalent Sm(4) atoms. In the eleventh O site, O(11) is bonded to one Sm(3), one Sm(7), and two equivalent Sm(5) atoms to form OSm4 tetrahedra that share corners with two equivalent O(7)Sm3Ti tetrahedra, corners with two equivalent O(1)Sm4 tetrahedra, corners with two equivalent O(11)Sm4 tetrahedra, corners with two equivalent O(8)Sm3Ti trigonal pyramids, and edges with two equivalent O(18)Sm3Ti tetrahedra. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Ti(2) and two equivalent Ti(3) atoms. In the thirteenth O site, O(13) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Mg(1), one Sm(8), and two equivalent Sm(6) atoms. In the fourteenth O site, O(14) is bonded in a 6-coordinate geometry to one Sm(4), two equivalent Sm(5), two equivalent Sm(6), and one Ti(4) atom. In the fifteenth O site, O(15) is bonded in a 4-coordinate geometry to one Sm(1), two equivalent Sm(7), and one Ti(3) atom. In the sixteenth O site, O(16) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Sm(2), two equivalent Sm(6), and one Ti(4) atom. In the seventeenth O site, O(17) is bonded to one Sm(1), two equivalent Sm(8), and one Ti(3) atom to form OSm3Ti tetrahedra that share corners with two equivalent O(17)Sm3Ti tetrahedra, corners with two equivalent O(1)Sm4 tetrahedra, corners with two equivalent O(20)Sm4 tetrahedra, corners with two equivalent O(8)Sm3Ti trigonal pyramids, and  an edgeedge with one O(20)Sm4 tetrahedra. In the eighteenth O site, O(18) is bonded to one Sm(5), two equivalent Sm(7), and one Ti(1) atom to form OSm3Ti tetrahedra that share corners with two equivalent O(18)Sm3Ti tetrahedra, corners with two equivalent O(7)Sm3Ti tetrahedra, corners with two equivalent O(1)Sm4 tetrahedra, corners with two equivalent O(2)SmTi3 trigonal pyramids, and edges with two equivalent O(11)Sm4 tetrahedra. In the nineteenth O site, O(19) is bonded in a 2-coordinate geometry to one Sm(5), one Sm(6), and two equivalent Ti(4) atoms. In the twentieth O site, O(20) is bonded to one Sm(2), one Sm(6), and two equivalent Sm(8) atoms to form distorted OSm4 tetrahedra that share corners with two equivalent O(17)Sm3Ti tetrahedra, corners with two equivalent O(3)Sm3Ti tetrahedra, corners with two equivalent O(20)Sm4 tetrahedra, and  an edgeedge with one O(17)Sm3Ti tetrahedra.
MgSm8Ti4O20 crystallizes in the monoclinic Pm space group. Mg(1) is bonded in a 6-coordinate geometry to one O(10), one O(9), two equivalent O(13), and two equivalent O(6) atoms. The Mg(1)-O(10) bond length is 2.08 Å. The Mg(1)-O(9) bond length is 2.02 Å. Both Mg(1)-O(13) bond lengths are 2.16 Å. Both Mg(1)-O(6) bond lengths are 2.53 Å. There are eight inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 7-coordinate geometry to one O(15), one O(17), one O(8), two equivalent O(1), and two equivalent O(4) atoms. The Sm(1)-O(15) bond length is 2.73 Å. The Sm(1)-O(17) bond length is 2.31 Å. The Sm(1)-O(8) bond length is 2.75 Å. Both Sm(1)-O(1) bond lengths are 2.27 Å. Both Sm(1)-O(4) bond lengths are 2.48 Å. In the second Sm site, Sm(2) is bonded in a 8-coordinate geometry to one O(10), one O(20), two equivalent O(16), two equivalent O(3), and two equivalent O(6) atoms. The Sm(2)-O(10) bond length is 2.68 Å. The Sm(2)-O(20) bond length is 2.26 Å. Both Sm(2)-O(16) bond lengths are 2.76 Å. Both Sm(2)-O(3) bond lengths are 2.38 Å. Both Sm(2)-O(6) bond lengths are 2.47 Å. In the third Sm site, Sm(3) is bonded to one O(1), one O(11), two equivalent O(5), and two equivalent O(8) atoms to form distorted SmO6 octahedra that share corners with two equivalent Sm(7)O6 octahedra, corners with two equivalent Ti(3)O6 octahedra, corners with two equivalent Sm(5)O7 pentagonal bipyramids, corners with two equivalent Ti(1)O5 trigonal bipyramids, and edges with two equivalent Sm(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-68°. The Sm(3)-O(1) bond length is 2.42 Å. The Sm(3)-O(11) bond length is 2.37 Å. Both Sm(3)-O(5) bond lengths are 2.42 Å. Both Sm(3)-O(8) bond lengths are 2.32 Å. In the fourth Sm site, Sm(4) is bonded in a 7-coordinate geometry to one O(14), one O(2), one O(3), two equivalent O(10), and two equivalent O(7) atoms. The Sm(4)-O(14) bond length is 2.34 Å. The Sm(4)-O(2) bond length is 2.68 Å. The Sm(4)-O(3) bond length is 2.20 Å. Both Sm(4)-O(10) bond lengths are 2.52 Å. Both Sm(4)-O(7) bond lengths are 2.28 Å. In the fifth Sm site, Sm(5) is bonded to one O(18), one O(19), one O(7), two equivalent O(11), and two equivalent O(14) atoms to form distorted SmO7 pentagonal bipyramids that share corners with two equivalent Sm(3)O6 octahedra, corners with two equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Sm(7)O6 octahedra, and edges with two equivalent Sm(5)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 59°. The Sm(5)-O(18) bond length is 2.46 Å. The Sm(5)-O(19) bond length is 2.48 Å. The Sm(5)-O(7) bond length is 2.43 Å. Both Sm(5)-O(11) bond lengths are 2.42 Å. Both Sm(5)-O(14) bond lengths are 2.47 Å. In the sixth Sm site, Sm(6) is bonded in a 9-coordinate geometry to one O(10), one O(19), one O(20), two equivalent O(13), two equivalent O(14), and two equivalent O(16) atoms. The Sm(6)-O(10) bond length is 2.30 Å. The Sm(6)-O(19) bond length is 2.79 Å. The Sm(6)-O(20) bond length is 2.47 Å. Both Sm(6)-O(13) bond lengths are 2.77 Å. Both Sm(6)-O(14) bond lengths are 2.93 Å. Both Sm(6)-O(16) bond lengths are 2.26 Å. In the seventh Sm site, Sm(7) is bonded to one O(1), one O(11), two equivalent O(15), and two equivalent O(18) atoms to form SmO6 octahedra that share corners with two equivalent Sm(3)O6 octahedra, corners with two equivalent Ti(3)O6 octahedra, corners with two equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Sm(7)O6 octahedra, and edges with two equivalent Sm(5)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 51-68°. The Sm(7)-O(1) bond length is 2.34 Å. The Sm(7)-O(11) bond length is 2.37 Å. Both Sm(7)-O(15) bond lengths are 2.44 Å. Both Sm(7)-O(18) bond lengths are 2.31 Å. In the eighth Sm site, Sm(8) is bonded to one O(13), one O(4), two equivalent O(17), and two equivalent O(20) atoms to form distorted SmO6 octahedra that share corners with two equivalent Ti(3)O6 octahedra,  a cornercorner with one Ti(2)O5 trigonal bipyramid, and edges with two equivalent Sm(8)O6 octahedra. The corner-sharing octahedral tilt angles are 61°. The Sm(8)-O(13) bond length is 2.24 Å. The Sm(8)-O(4) bond length is 2.59 Å. Both Sm(8)-O(17) bond lengths are 2.41 Å. Both Sm(8)-O(20) bond lengths are 2.30 Å. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(18), one O(5), one O(7), and two equivalent O(2) atoms to form TiO5 trigonal bipyramids that share corners with two equivalent Sm(3)O6 octahedra, corners with two equivalent Sm(7)O6 octahedra, corners with two equivalent Sm(5)O7 pentagonal bipyramids, and corners with two equivalent Ti(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 50-68°. The Ti(1)-O(18) bond length is 2.08 Å. The Ti(1)-O(5) bond length is 1.79 Å. The Ti(1)-O(7) bond length is 2.04 Å. Both Ti(1)-O(2) bond lengths are 2.00 Å. In the second Ti site, Ti(2) is bonded to one O(12), one O(4), one O(6), and two equivalent O(9) atoms to form distorted TiO5 trigonal bipyramids that share  a cornercorner with one Sm(8)O6 octahedra, corners with two equivalent Ti(2)O5 trigonal bipyramids, and edges with two equivalent Ti(3)O6 octahedra. The corner-sharing octahedral tilt angles are 58°. The Ti(2)-O(12) bond length is 2.14 Å. The Ti(2)-O(4) bond length is 1.85 Å. The Ti(2)-O(6) bond length is 1.96 Å. Both Ti(2)-O(9) bond lengths are 1.95 Å. In the third Ti site, Ti(3) is bonded to one O(15), one O(17), one O(8), one O(9), and two equivalent O(12) atoms to form distorted TiO6 octahedra that share corners with two equivalent Sm(3)O6 octahedra, corners with two equivalent Sm(7)O6 octahedra, corners with two equivalent Sm(8)O6 octahedra, corners with two equivalent Ti(3)O6 octahedra, and edges with two equivalent Ti(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 38-65°. The Ti(3)-O(15) bond length is 1.89 Å. The Ti(3)-O(17) bond length is 2.10 Å. The Ti(3)-O(8) bond length is 2.18 Å. The Ti(3)-O(9) bond length is 2.43 Å. Both Ti(3)-O(12) bond lengths are 1.94 Å. In the fourth Ti site, Ti(4) is bonded in a 6-coordinate geometry to one O(14), one O(16), one O(2), one O(3), and two equivalent O(19) atoms. The Ti(4)-O(14) bond length is 2.29 Å. The Ti(4)-O(16) bond length is 2.02 Å. The Ti(4)-O(2) bond length is 2.19 Å. The Ti(4)-O(3) bond length is 1.94 Å. Both Ti(4)-O(19) bond lengths are 1.89 Å. There are twenty inequivalent O sites. In the first O site, O(1) is bonded to one Sm(3), one Sm(7), and two equivalent Sm(1) atoms to form OSm4 tetrahedra that share corners with two equivalent O(17)Sm3Ti tetrahedra, corners with two equivalent O(18)Sm3Ti tetrahedra, corners with two equivalent O(1)Sm4 tetrahedra, corners with two equivalent O(11)Sm4 tetrahedra, and edges with two equivalent O(8)Sm3Ti trigonal pyramids. In the second O site, O(2) is bonded to one Sm(4), one Ti(4), and two equivalent Ti(1) atoms to form distorted OSmTi3 trigonal pyramids that share corners with two equivalent O(18)Sm3Ti tetrahedra, corners with two equivalent O(2)SmTi3 trigonal pyramids,  an edgeedge with one O(3)Sm3Ti tetrahedra, and edges with two equivalent O(7)Sm3Ti tetrahedra. In the third O site, O(3) is bonded to one Sm(4), two equivalent Sm(2), and one Ti(4) atom to form OSm3Ti tetrahedra that share corners with two equivalent O(3)Sm3Ti tetrahedra, corners with two equivalent O(7)Sm3Ti tetrahedra, corners with two equivalent O(20)Sm4 tetrahedra, and  an edgeedge with one O(2)SmTi3 trigonal pyramid. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Sm(8), two equivalent Sm(1), and one Ti(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Sm(3) and one Ti(1) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to two equivalent Mg(1), two equivalent Sm(2), and one Ti(2) atom. In the seventh O site, O(7) is bonded to one Sm(5), two equivalent Sm(4), and one Ti(1) atom to form OSm3Ti tetrahedra that share corners with two equivalent O(18)Sm3Ti tetrahedra, corners with two equivalent O(3)Sm3Ti tetrahedra, corners with two equivalent O(7)Sm3Ti tetrahedra, corners with two equivalent O(11)Sm4 tetrahedra, and edges with two equivalent O(2)SmTi3 trigonal pyramids. In the eighth O site, O(8) is bonded to one Sm(1), two equivalent Sm(3), and one Ti(3) atom to form distorted OSm3Ti trigonal pyramids that share corners with two equivalent O(17)Sm3Ti tetrahedra, corners with two equivalent O(11)Sm4 tetrahedra, corners with two equivalent O(8)Sm3Ti trigonal pyramids, and edges with two equivalent O(1)Sm4 tetrahedra. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Mg(1), one Ti(3), and two equivalent Ti(2) atoms. In the tenth O site, O(10) is bonded in a 5-coordinate geometry to one Mg(1), one Sm(2), one Sm(6), and two equivalent Sm(4) atoms. In the eleventh O site, O(11) is bonded to one Sm(3), one Sm(7), and two equivalent Sm(5) atoms to form OSm4 tetrahedra that share corners with two equivalent O(7)Sm3Ti tetrahedra, corners with two equivalent O(1)Sm4 tetrahedra, corners with two equivalent O(11)Sm4 tetrahedra, corners with two equivalent O(8)Sm3Ti trigonal pyramids, and edges with two equivalent O(18)Sm3Ti tetrahedra. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Ti(2) and two equivalent Ti(3) atoms. In the thirteenth O site, O(13) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Mg(1), one Sm(8), and two equivalent Sm(6) atoms. In the fourteenth O site, O(14) is bonded in a 6-coordinate geometry to one Sm(4), two equivalent Sm(5), two equivalent Sm(6), and one Ti(4) atom. In the fifteenth O site, O(15) is bonded in a 4-coordinate geometry to one Sm(1), two equivalent Sm(7), and one Ti(3) atom. In the sixteenth O site, O(16) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Sm(2), two equivalent Sm(6), and one Ti(4) atom. In the seventeenth O site, O(17) is bonded to one Sm(1), two equivalent Sm(8), and one Ti(3) atom to form OSm3Ti tetrahedra that share corners with two equivalent O(17)Sm3Ti tetrahedra, corners with two equivalent O(1)Sm4 tetrahedra, corners with two equivalent O(20)Sm4 tetrahedra, corners with two equivalent O(8)Sm3Ti trigonal pyramids, and  an edgeedge with one O(20)Sm4 tetrahedra. In the eighteenth O site, O(18) is bonded to one Sm(5), two equivalent Sm(7), and one Ti(1) atom to form OSm3Ti tetrahedra that share corners with two equivalent O(18)Sm3Ti tetrahedra, corners with two equivalent O(7)Sm3Ti tetrahedra, corners with two equivalent O(1)Sm4 tetrahedra, corners with two equivalent O(2)SmTi3 trigonal pyramids, and edges with two equivalent O(11)Sm4 tetrahedra. In the nineteenth O site, O(19) is bonded in a 2-coordinate geometry to one Sm(5), one Sm(6), and two equivalent Ti(4) atoms. In the twentieth O site, O(20) is bonded to one Sm(2), one Sm(6), and two equivalent Sm(8) atoms to form distorted OSm4 tetrahedra that share corners with two equivalent O(17)Sm3Ti tetrahedra, corners with two equivalent O(3)Sm3Ti tetrahedra, corners with two equivalent O(20)Sm4 tetrahedra, and  an edgeedge with one O(17)Sm3Ti tetrahedra.