Na2Ti(SiO4)2 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(5), one O(7), and two equivalent O(6) atoms. In the second Na site, Na(2) is bonded to two equivalent O(4) and four equivalent O(8) atoms to form distorted NaO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Na(3)O4 trigonal pyramids, edges with two equivalent Na(2)O6 octahedra, and  an edgeedge with one Na(3)O4 trigonal pyramid. In the third Na site, Na(3) is bonded to four equivalent O(4) atoms to form distorted NaO4 trigonal pyramids that share corners with two equivalent Na(2)O6 octahedra, corners with four equivalent Si(2)O4 tetrahedra,  an edgeedge with one Na(2)O6 octahedra, and edges with two equivalent Na(3)O4 trigonal pyramids. The corner-sharing octahedral tilt angles are 79°. Ti(1) is bonded to one O(2), one O(3), two equivalent O(5), and two equivalent O(7) atoms to form TiO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, and edges with two equivalent Ti(1)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(7), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with three equivalent Ti(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-56°. In the second Si site, Si(2) is bonded to one O(3), one O(4), and two equivalent O(6) atoms to form SiO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra,  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Na(3)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 30-50°. There are eight inequivalent O sites. In the first O site, O(7) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), two equivalent Ti(1), and one Si(1) atom. In the second O site, O(8) is bonded in a water-like geometry to two equivalent Na(2) atoms. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Na(1) and two equivalent Si(1) atoms. In the fourth O site, O(2) is bonded in a distorted T-shaped geometry to one Na(1), one Ti(1), and one Si(1) atom. In the fifth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent Na(1) and two equivalent Si(2) atoms. In the sixth O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Ti(1), and one Si(2) atom. In the seventh O site, O(4) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(3), and one Si(2) atom. In the eighth O site, O(5) is bonded in a trigonal non-coplanar geometry to one Na(1) and two equivalent Ti(1) atoms.
Na2Ti(SiO4)2 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(5), one O(7), and two equivalent O(6) atoms. The Na(1)-O(1) bond length is 2.39 Å. The Na(1)-O(2) bond length is 2.49 Å. The Na(1)-O(3) bond length is 2.34 Å. The Na(1)-O(5) bond length is 2.37 Å. The Na(1)-O(7) bond length is 2.55 Å. There is one shorter (2.54 Å) and one longer (2.70 Å) Na(1)-O(6) bond length. In the second Na site, Na(2) is bonded to two equivalent O(4) and four equivalent O(8) atoms to form distorted NaO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Na(3)O4 trigonal pyramids, edges with two equivalent Na(2)O6 octahedra, and  an edgeedge with one Na(3)O4 trigonal pyramid. Both Na(2)-O(4) bond lengths are 2.31 Å. There are two shorter (2.48 Å) and two longer (2.59 Å) Na(2)-O(8) bond lengths. In the third Na site, Na(3) is bonded to four equivalent O(4) atoms to form distorted NaO4 trigonal pyramids that share corners with two equivalent Na(2)O6 octahedra, corners with four equivalent Si(2)O4 tetrahedra,  an edgeedge with one Na(2)O6 octahedra, and edges with two equivalent Na(3)O4 trigonal pyramids. The corner-sharing octahedral tilt angles are 79°. There are two shorter (2.22 Å) and two longer (2.35 Å) Na(3)-O(4) bond lengths. Ti(1) is bonded to one O(2), one O(3), two equivalent O(5), and two equivalent O(7) atoms to form TiO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, and edges with two equivalent Ti(1)O6 octahedra. The Ti(1)-O(2) bond length is 1.99 Å. The Ti(1)-O(3) bond length is 1.87 Å. There is one shorter (1.85 Å) and one longer (1.94 Å) Ti(1)-O(5) bond length. There is one shorter (2.14 Å) and one longer (2.16 Å) Ti(1)-O(7) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(7), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with three equivalent Ti(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-56°. The Si(1)-O(2) bond length is 1.62 Å. The Si(1)-O(7) bond length is 1.64 Å. Both Si(1)-O(1) bond lengths are 1.66 Å. In the second Si site, Si(2) is bonded to one O(3), one O(4), and two equivalent O(6) atoms to form SiO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra,  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Na(3)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 30-50°. The Si(2)-O(3) bond length is 1.64 Å. The Si(2)-O(4) bond length is 1.59 Å. There is one shorter (1.67 Å) and one longer (1.68 Å) Si(2)-O(6) bond length. There are eight inequivalent O sites. In the first O site, O(7) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), two equivalent Ti(1), and one Si(1) atom. In the second O site, O(8) is bonded in a water-like geometry to two equivalent Na(2) atoms. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Na(1) and two equivalent Si(1) atoms. In the fourth O site, O(2) is bonded in a distorted T-shaped geometry to one Na(1), one Ti(1), and one Si(1) atom. In the fifth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent Na(1) and two equivalent Si(2) atoms. In the sixth O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Ti(1), and one Si(2) atom. In the seventh O site, O(4) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(3), and one Si(2) atom. In the eighth O site, O(5) is bonded in a trigonal non-coplanar geometry to one Na(1) and two equivalent Ti(1) atoms.