Na2MgSm2Ti2O8 crystallizes in the tetragonal P-4m2 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 11-coordinate geometry to two equivalent Mg(1), two equivalent O(3), two equivalent O(4), and five equivalent O(2) atoms. In the second Na site, Na(1) is bonded in a 11-coordinate geometry to two equivalent Mg(1), two equivalent O(3), two equivalent O(4), and five equivalent O(2) atoms. Mg(1) is bonded in a 4-coordinate geometry to four Na(1,1) and four equivalent O(2) atoms. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 9-coordinate geometry to two equivalent O(3), two equivalent O(4), and five equivalent O(1) atoms. In the second Sm site, Sm(1) is bonded in a 9-coordinate geometry to two equivalent O(3), two equivalent O(4), and five equivalent O(1) atoms. Ti(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 6-17°. There are four inequivalent O sites. In the first O site, O(1) is bonded to five Sm(1,1) and one Ti(1) atom to form distorted OSm5Ti octahedra that share corners with four equivalent O(1)Sm5Ti octahedra, corners with six equivalent O(3)Na2Sm2Ti2 octahedra, corners with six equivalent O(4)Na2Sm2Ti2 octahedra, edges with eight equivalent O(1)Sm5Ti octahedra, faces with two equivalent O(3)Na2Sm2Ti2 octahedra, and faces with two equivalent O(4)Na2Sm2Ti2 octahedra. The corner-sharing octahedral tilt angles range from 18-53°. In the second O site, O(2) is bonded in a 8-coordinate geometry to five Na(1,1); two equivalent Mg(1); and one Ti(1) atom. In the third O site, O(3) is bonded to two equivalent Na(1), two equivalent Sm(1), and two equivalent Ti(1) atoms to form distorted ONa2Sm2Ti2 octahedra that share corners with two equivalent O(3)Na2Sm2Ti2 octahedra, corners with six equivalent O(1)Sm5Ti octahedra, edges with two equivalent O(3)Na2Sm2Ti2 octahedra, faces with two equivalent O(1)Sm5Ti octahedra, and faces with four equivalent O(4)Na2Sm2Ti2 octahedra. The corner-sharing octahedral tilt angles range from 6-51°. In the fourth O site, O(4) is bonded to two equivalent Na(1), two equivalent Sm(1), and two equivalent Ti(1) atoms to form distorted ONa2Sm2Ti2 octahedra that share corners with two equivalent O(4)Na2Sm2Ti2 octahedra, corners with six equivalent O(1)Sm5Ti octahedra, edges with two equivalent O(4)Na2Sm2Ti2 octahedra, faces with two equivalent O(1)Sm5Ti octahedra, and faces with four equivalent O(3)Na2Sm2Ti2 octahedra. The corner-sharing octahedral tilt angles range from 17-53°.
Na2MgSm2Ti2O8 crystallizes in the tetragonal P-4m2 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 11-coordinate geometry to two equivalent Mg(1), two equivalent O(3), two equivalent O(4), and five equivalent O(2) atoms. Both Na(1)-Mg(1) bond lengths are 2.56 Å. Both Na(1)-O(3) bond lengths are 2.39 Å. Both Na(1)-O(4) bond lengths are 2.51 Å. There is one shorter (2.51 Å) and four longer (2.88 Å) Na(1)-O(2) bond lengths. In the second Na site, Na(1) is bonded in a 11-coordinate geometry to two equivalent Mg(1), two equivalent O(3), two equivalent O(4), and five equivalent O(2) atoms. Both Na(1)-Mg(1) bond lengths are 2.56 Å. Both Na(1)-O(3) bond lengths are 2.39 Å. Both Na(1)-O(4) bond lengths are 2.51 Å. There is one shorter (2.51 Å) and four longer (2.88 Å) Na(1)-O(2) bond lengths. Mg(1) is bonded in a 4-coordinate geometry to four Na(1,1) and four equivalent O(2) atoms. All Mg(1)-O(2) bond lengths are 2.13 Å. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 9-coordinate geometry to two equivalent O(3), two equivalent O(4), and five equivalent O(1) atoms. Both Sm(1)-O(3) bond lengths are 2.57 Å. Both Sm(1)-O(4) bond lengths are 2.45 Å. There is one shorter (2.24 Å) and four longer (2.80 Å) Sm(1)-O(1) bond lengths. In the second Sm site, Sm(1) is bonded in a 9-coordinate geometry to two equivalent O(3), two equivalent O(4), and five equivalent O(1) atoms. Both Sm(1)-O(3) bond lengths are 2.57 Å. Both Sm(1)-O(4) bond lengths are 2.45 Å. There is one shorter (2.24 Å) and four longer (2.80 Å) Sm(1)-O(1) bond lengths. Ti(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 6-17°. The Ti(1)-O(1) bond length is 2.22 Å. The Ti(1)-O(2) bond length is 2.08 Å. Both Ti(1)-O(3) bond lengths are 1.96 Å. Both Ti(1)-O(4) bond lengths are 1.98 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to five Sm(1,1) and one Ti(1) atom to form distorted OSm5Ti octahedra that share corners with four equivalent O(1)Sm5Ti octahedra, corners with six equivalent O(3)Na2Sm2Ti2 octahedra, corners with six equivalent O(4)Na2Sm2Ti2 octahedra, edges with eight equivalent O(1)Sm5Ti octahedra, faces with two equivalent O(3)Na2Sm2Ti2 octahedra, and faces with two equivalent O(4)Na2Sm2Ti2 octahedra. The corner-sharing octahedral tilt angles range from 18-53°. In the second O site, O(2) is bonded in a 8-coordinate geometry to five Na(1,1); two equivalent Mg(1); and one Ti(1) atom. In the third O site, O(3) is bonded to two equivalent Na(1), two equivalent Sm(1), and two equivalent Ti(1) atoms to form distorted ONa2Sm2Ti2 octahedra that share corners with two equivalent O(3)Na2Sm2Ti2 octahedra, corners with six equivalent O(1)Sm5Ti octahedra, edges with two equivalent O(3)Na2Sm2Ti2 octahedra, faces with two equivalent O(1)Sm5Ti octahedra, and faces with four equivalent O(4)Na2Sm2Ti2 octahedra. The corner-sharing octahedral tilt angles range from 6-51°. In the fourth O site, O(4) is bonded to two equivalent Na(1), two equivalent Sm(1), and two equivalent Ti(1) atoms to form distorted ONa2Sm2Ti2 octahedra that share corners with two equivalent O(4)Na2Sm2Ti2 octahedra, corners with six equivalent O(1)Sm5Ti octahedra, edges with two equivalent O(4)Na2Sm2Ti2 octahedra, faces with two equivalent O(1)Sm5Ti octahedra, and faces with four equivalent O(3)Na2Sm2Ti2 octahedra. The corner-sharing octahedral tilt angles range from 17-53°.