K2Na3TlO4 crystallizes in the orthorhombic Pnnm space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted KO6 octahedra that share corners with two equivalent Na(2)O4 tetrahedra, corners with two equivalent Tl(1)O4 tetrahedra, corners with eight equivalent Na(1)O4 tetrahedra, edges with two equivalent K(1)O6 octahedra, edges with two equivalent Na(1)O4 tetrahedra, edges with two equivalent Na(2)O4 tetrahedra, and edges with two equivalent Tl(1)O4 tetrahedra. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(1), one O(3), and four equivalent O(2) atoms. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted NaO4 tetrahedra that share corners with four equivalent K(1)O6 octahedra, corners with two equivalent Na(1)O4 tetrahedra, corners with two equivalent Na(2)O4 tetrahedra, corners with two equivalent Tl(1)O4 tetrahedra,  an edgeedge with one K(1)O6 octahedra,  an edgeedge with one Na(1)O4 tetrahedra,  an edgeedge with one Na(2)O4 tetrahedra, and  an edgeedge with one Tl(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 26-47°. In the second Na site, Na(2) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted NaO4 tetrahedra that share corners with two equivalent K(1)O6 octahedra, corners with two equivalent Tl(1)O4 tetrahedra, corners with four equivalent Na(1)O4 tetrahedra, edges with two equivalent K(1)O6 octahedra,  an edgeedge with one Tl(1)O4 tetrahedra, and edges with two equivalent Na(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 48°. Tl(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form TlO4 tetrahedra that share corners with two equivalent K(1)O6 octahedra, corners with two equivalent Na(2)O4 tetrahedra, corners with four equivalent Na(1)O4 tetrahedra, edges with two equivalent K(1)O6 octahedra,  an edgeedge with one Na(2)O4 tetrahedra, and edges with two equivalent Na(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 53°. There are three inequivalent O sites. In the first O site, O(3) is bonded in a 7-coordinate geometry to one K(2), two equivalent K(1), one Na(2), two equivalent Na(1), and one Tl(1) atom. In the second O site, O(1) is bonded in a 7-coordinate geometry to one K(2), two equivalent K(1), one Na(2), two equivalent Na(1), and one Tl(1) atom. In the third O site, O(2) is bonded in a 7-coordinate geometry to one K(1), two equivalent K(2), one Na(2), two equivalent Na(1), and one Tl(1) atom.
K2Na3TlO4 crystallizes in the orthorhombic Pnnm space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted KO6 octahedra that share corners with two equivalent Na(2)O4 tetrahedra, corners with two equivalent Tl(1)O4 tetrahedra, corners with eight equivalent Na(1)O4 tetrahedra, edges with two equivalent K(1)O6 octahedra, edges with two equivalent Na(1)O4 tetrahedra, edges with two equivalent Na(2)O4 tetrahedra, and edges with two equivalent Tl(1)O4 tetrahedra. Both K(1)-O(1) bond lengths are 2.87 Å. Both K(1)-O(2) bond lengths are 2.79 Å. Both K(1)-O(3) bond lengths are 2.94 Å. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(1), one O(3), and four equivalent O(2) atoms. The K(2)-O(1) bond length is 2.88 Å. The K(2)-O(3) bond length is 2.75 Å. There are two shorter (2.99 Å) and two longer (3.21 Å) K(2)-O(2) bond lengths. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted NaO4 tetrahedra that share corners with four equivalent K(1)O6 octahedra, corners with two equivalent Na(1)O4 tetrahedra, corners with two equivalent Na(2)O4 tetrahedra, corners with two equivalent Tl(1)O4 tetrahedra,  an edgeedge with one K(1)O6 octahedra,  an edgeedge with one Na(1)O4 tetrahedra,  an edgeedge with one Na(2)O4 tetrahedra, and  an edgeedge with one Tl(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 26-47°. The Na(1)-O(1) bond length is 2.34 Å. The Na(1)-O(3) bond length is 2.30 Å. There is one shorter (2.30 Å) and one longer (2.37 Å) Na(1)-O(2) bond length. In the second Na site, Na(2) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted NaO4 tetrahedra that share corners with two equivalent K(1)O6 octahedra, corners with two equivalent Tl(1)O4 tetrahedra, corners with four equivalent Na(1)O4 tetrahedra, edges with two equivalent K(1)O6 octahedra,  an edgeedge with one Tl(1)O4 tetrahedra, and edges with two equivalent Na(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 48°. The Na(2)-O(1) bond length is 2.36 Å. The Na(2)-O(3) bond length is 2.47 Å. Both Na(2)-O(2) bond lengths are 2.20 Å. Tl(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form TlO4 tetrahedra that share corners with two equivalent K(1)O6 octahedra, corners with two equivalent Na(2)O4 tetrahedra, corners with four equivalent Na(1)O4 tetrahedra, edges with two equivalent K(1)O6 octahedra,  an edgeedge with one Na(2)O4 tetrahedra, and edges with two equivalent Na(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 53°. The Tl(1)-O(1) bond length is 2.24 Å. The Tl(1)-O(3) bond length is 2.19 Å. Both Tl(1)-O(2) bond lengths are 2.15 Å. There are three inequivalent O sites. In the first O site, O(3) is bonded in a 7-coordinate geometry to one K(2), two equivalent K(1), one Na(2), two equivalent Na(1), and one Tl(1) atom. In the second O site, O(1) is bonded in a 7-coordinate geometry to one K(2), two equivalent K(1), one Na(2), two equivalent Na(1), and one Tl(1) atom. In the third O site, O(2) is bonded in a 7-coordinate geometry to one K(1), two equivalent K(2), one Na(2), two equivalent Na(1), and one Tl(1) atom.