Na2Zn2Si2O7 crystallizes in the orthorhombic Ama2 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(4), two equivalent O(1), and two equivalent O(3) atoms. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. Zn(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted ZnO4 tetrahedra that share corners with two equivalent Zn(1)O4 tetrahedra and corners with four 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  a cornercorner with one Si(1)O4 tetrahedra and corners with four equivalent Zn(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(3) is bonded to one Na(1), one Na(2), one Zn(1), and one Si(1) atom to form a mixture of distorted edge and corner-sharing ONa2ZnSi trigonal pyramids. In the second O site, O(4) is bonded in a 2-coordinate geometry to one Na(1) and two equivalent Si(1) atoms. In the third O site, O(1) is bonded to one Na(1), one Na(2), one Zn(1), and one Si(1) atom to form a mixture of distorted edge and corner-sharing ONa2ZnSi trigonal pyramids. In the fourth O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Na(2), two equivalent Zn(1), and one Si(1) atom.
Na2Zn2Si2O7 crystallizes in the orthorhombic Ama2 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(4), two equivalent O(1), and two equivalent O(3) atoms. The Na(1)-O(4) bond length is 2.66 Å. Both Na(1)-O(1) bond lengths are 2.41 Å. Both Na(1)-O(3) bond lengths are 2.47 Å. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. Both Na(2)-O(1) bond lengths are 2.47 Å. Both Na(2)-O(3) bond lengths are 2.35 Å. There are two shorter (2.80 Å) and two longer (2.89 Å) Na(2)-O(2) bond lengths. Zn(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted ZnO4 tetrahedra that share corners with two equivalent Zn(1)O4 tetrahedra and corners with four equivalent Si(1)O4 tetrahedra. The Zn(1)-O(1) bond length is 1.92 Å. The Zn(1)-O(3) bond length is 1.98 Å. There is one shorter (2.00 Å) and one longer (2.09 Å) Zn(1)-O(2) bond length. 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  a cornercorner with one Si(1)O4 tetrahedra and corners with four equivalent Zn(1)O4 tetrahedra. The Si(1)-O(1) bond length is 1.63 Å. The Si(1)-O(2) bond length is 1.66 Å. The Si(1)-O(3) bond length is 1.63 Å. The Si(1)-O(4) bond length is 1.68 Å. There are four inequivalent O sites. In the first O site, O(3) is bonded to one Na(1), one Na(2), one Zn(1), and one Si(1) atom to form a mixture of distorted edge and corner-sharing ONa2ZnSi trigonal pyramids. In the second O site, O(4) is bonded in a 2-coordinate geometry to one Na(1) and two equivalent Si(1) atoms. In the third O site, O(1) is bonded to one Na(1), one Na(2), one Zn(1), and one Si(1) atom to form a mixture of distorted edge and corner-sharing ONa2ZnSi trigonal pyramids. In the fourth O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Na(2), two equivalent Zn(1), and one Si(1) atom.