NaNd3Ti2(SbO7)2 crystallizes in the monoclinic C2/m space group. Na(1) is bonded to two equivalent O(2), two equivalent O(5), and four equivalent O(4) atoms to form distorted NaO8 hexagonal bipyramids that share edges with two equivalent Nd(1)O8 hexagonal bipyramids, edges with four equivalent Nd(2)O8 hexagonal bipyramids, edges with two equivalent Ti(2)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. There are two inequivalent Nd sites. In the first Nd site, Nd(1) is bonded to two equivalent O(2), two equivalent O(5), and four equivalent O(3) atoms to form distorted NdO8 hexagonal bipyramids that share edges with two equivalent Na(1)O8 hexagonal bipyramids, edges with four equivalent Nd(2)O8 hexagonal bipyramids, edges with two equivalent Ti(1)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. In the second Nd site, Nd(2) is bonded to two equivalent O(1), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted NdO8 hexagonal bipyramids that share edges with two equivalent Na(1)O8 hexagonal bipyramids, edges with two equivalent Nd(1)O8 hexagonal bipyramids, edges with two equivalent Nd(2)O8 hexagonal bipyramids, edges with two equivalent Ti(1)O6 octahedra, edges with two equivalent Ti(2)O6 octahedra, and edges with two equivalent Sb(1)O6 octahedra. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form TiO6 octahedra that share corners with two equivalent Ti(2)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra, edges with two equivalent Nd(1)O8 hexagonal bipyramids, and edges with four equivalent Nd(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 43-46°. In the second Ti site, Ti(2) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form TiO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra, edges with two equivalent Na(1)O8 hexagonal bipyramids, and edges with four equivalent Nd(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 43°. Sb(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form SbO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Ti(2)O6 octahedra, corners with two equivalent Sb(1)O6 octahedra, edges with two equivalent Na(1)O8 hexagonal bipyramids, edges with two equivalent Nd(1)O8 hexagonal bipyramids, and edges with two equivalent Nd(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 43-46°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Nd(2), one Ti(1), and one Ti(2) atom. In the second O site, O(2) is bonded to one Na(1), one Nd(1), and two equivalent Sb(1) atoms to form distorted ONaNdSb2 tetrahedra that share corners with two equivalent O(5)NaNd3 tetrahedra, corners with four equivalent O(2)NaNdSb2 tetrahedra, and  an edgeedge with one O(5)NaNd3 tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Nd(1), one Nd(2), one Ti(1), and one Sb(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Nd(2), one Ti(2), and one Sb(1) atom. In the fifth O site, O(5) is bonded to one Na(1), one Nd(1), and two equivalent Nd(2) atoms to form ONaNd3 tetrahedra that share corners with two equivalent O(2)NaNdSb2 tetrahedra, corners with four equivalent O(5)NaNd3 tetrahedra, and  an edgeedge with one O(2)NaNdSb2 tetrahedra.
NaNd3Ti2(SbO7)2 crystallizes in the monoclinic C2/m space group. Na(1) is bonded to two equivalent O(2), two equivalent O(5), and four equivalent O(4) atoms to form distorted NaO8 hexagonal bipyramids that share edges with two equivalent Nd(1)O8 hexagonal bipyramids, edges with four equivalent Nd(2)O8 hexagonal bipyramids, edges with two equivalent Ti(2)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. Both Na(1)-O(2) bond lengths are 2.63 Å. Both Na(1)-O(5) bond lengths are 2.27 Å. All Na(1)-O(4) bond lengths are 2.71 Å. There are two inequivalent Nd sites. In the first Nd site, Nd(1) is bonded to two equivalent O(2), two equivalent O(5), and four equivalent O(3) atoms to form distorted NdO8 hexagonal bipyramids that share edges with two equivalent Na(1)O8 hexagonal bipyramids, edges with four equivalent Nd(2)O8 hexagonal bipyramids, edges with two equivalent Ti(1)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. Both Nd(1)-O(2) bond lengths are 2.54 Å. Both Nd(1)-O(5) bond lengths are 2.26 Å. All Nd(1)-O(3) bond lengths are 2.62 Å. In the second Nd site, Nd(2) is bonded to two equivalent O(1), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted NdO8 hexagonal bipyramids that share edges with two equivalent Na(1)O8 hexagonal bipyramids, edges with two equivalent Nd(1)O8 hexagonal bipyramids, edges with two equivalent Nd(2)O8 hexagonal bipyramids, edges with two equivalent Ti(1)O6 octahedra, edges with two equivalent Ti(2)O6 octahedra, and edges with two equivalent Sb(1)O6 octahedra. Both Nd(2)-O(1) bond lengths are 2.66 Å. Both Nd(2)-O(3) bond lengths are 2.60 Å. Both Nd(2)-O(4) bond lengths are 2.57 Å. Both Nd(2)-O(5) bond lengths are 2.26 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form TiO6 octahedra that share corners with two equivalent Ti(2)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra, edges with two equivalent Nd(1)O8 hexagonal bipyramids, and edges with four equivalent Nd(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 43-46°. Both Ti(1)-O(1) bond lengths are 1.96 Å. All Ti(1)-O(3) bond lengths are 2.00 Å. In the second Ti site, Ti(2) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form TiO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra, edges with two equivalent Na(1)O8 hexagonal bipyramids, and edges with four equivalent Nd(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 43°. Both Ti(2)-O(1) bond lengths are 1.98 Å. All Ti(2)-O(4) bond lengths are 2.00 Å. Sb(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form SbO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Ti(2)O6 octahedra, corners with two equivalent Sb(1)O6 octahedra, edges with two equivalent Na(1)O8 hexagonal bipyramids, edges with two equivalent Nd(1)O8 hexagonal bipyramids, and edges with two equivalent Nd(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 43-46°. Both Sb(1)-O(2) bond lengths are 2.03 Å. Both Sb(1)-O(3) bond lengths are 2.01 Å. Both Sb(1)-O(4) bond lengths are 1.99 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Nd(2), one Ti(1), and one Ti(2) atom. In the second O site, O(2) is bonded to one Na(1), one Nd(1), and two equivalent Sb(1) atoms to form distorted ONaNdSb2 tetrahedra that share corners with two equivalent O(5)NaNd3 tetrahedra, corners with four equivalent O(2)NaNdSb2 tetrahedra, and  an edgeedge with one O(5)NaNd3 tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Nd(1), one Nd(2), one Ti(1), and one Sb(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Nd(2), one Ti(2), and one Sb(1) atom. In the fifth O site, O(5) is bonded to one Na(1), one Nd(1), and two equivalent Nd(2) atoms to form ONaNd3 tetrahedra that share corners with two equivalent O(2)NaNdSb2 tetrahedra, corners with four equivalent O(5)NaNd3 tetrahedra, and  an edgeedge with one O(2)NaNdSb2 tetrahedra.