Na3ScSi2O7 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 4-coordinate geometry to one O(1), one O(3), and two equivalent O(2) atoms. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(4), two equivalent O(1), and two equivalent O(3) atoms. Sc(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form ScO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with three equivalent Sc(1)O6 octahedra and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 17-43°. There are four inequivalent O sites. In the first O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Na(2) and two equivalent Si(1) atoms. In the second O site, O(1) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Sc(1), and one Si(1) atom. In the third O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Sc(1), and one Si(1) atom. In the fourth O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Sc(1), and one Si(1) atom.
Na3ScSi2O7 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 4-coordinate geometry to one O(1), one O(3), and two equivalent O(2) atoms. The Na(1)-O(1) bond length is 2.50 Å. The Na(1)-O(3) bond length is 2.38 Å. There is one shorter (2.37 Å) and one longer (2.50 Å) Na(1)-O(2) bond length. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(4), two equivalent O(1), and two equivalent O(3) atoms. The Na(2)-O(4) bond length is 2.50 Å. Both Na(2)-O(1) bond lengths are 2.38 Å. Both Na(2)-O(3) bond lengths are 2.45 Å. Sc(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form ScO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra. Both Sc(1)-O(1) bond lengths are 2.15 Å. Both Sc(1)-O(2) bond lengths are 2.08 Å. Both Sc(1)-O(3) bond lengths are 2.16 Å. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with three equivalent Sc(1)O6 octahedra and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 17-43°. The Si(1)-O(1) bond length is 1.63 Å. The Si(1)-O(2) bond length is 1.63 Å. The Si(1)-O(3) bond length is 1.64 Å. The Si(1)-O(4) bond length is 1.68 Å. There are four inequivalent O sites. In the first O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Na(2) and two equivalent Si(1) atoms. In the second O site, O(1) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Sc(1), and one Si(1) atom. In the third O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Sc(1), and one Si(1) atom. In the fourth O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Sc(1), and one Si(1) atom.