K2MgLa2Ti3O10 crystallizes in the tetragonal I-4m2 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 11-coordinate geometry to two equivalent Mg(1), two equivalent O(2), two equivalent O(3), and five equivalent O(1) atoms. In the second K site, K(1) is bonded in a 11-coordinate geometry to two equivalent Mg(1), two equivalent O(2), two equivalent O(3), and five equivalent O(1) atoms. Mg(1) is bonded in a 4-coordinate geometry to four equivalent K(1) and four equivalent O(1) atoms. La(1) is bonded to two equivalent O(2), two equivalent O(3), four equivalent O(4), and four equivalent O(5) atoms to form LaO12 cuboctahedra that share corners with eight equivalent La(1)O12 cuboctahedra, faces with five equivalent La(1)O12 cuboctahedra, faces with four equivalent Ti(1)O6 octahedra, and faces with four equivalent Ti(2)O6 octahedra. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form TiO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, and faces with four equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-11°. In the second Ti site, Ti(2) is bonded to two equivalent O(4) and four equivalent O(5) atoms to form TiO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra, and faces with eight equivalent La(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to five equivalent K(1), two equivalent Mg(1), and one Ti(1) atom. In the second O site, O(2) is bonded to two equivalent K(1), two equivalent La(1), and two equivalent Ti(1) atoms to form a mixture of distorted face, corner, and edge-sharing OK2La2Ti2 octahedra. The corner-sharing octahedral tilt angles are 7°. In the third O site, O(3) is bonded to two equivalent K(1), two equivalent La(1), and two equivalent Ti(1) atoms to form a mixture of distorted face, corner, and edge-sharing OK2La2Ti2 octahedra. The corner-sharing octahedral tilt angles are 11°. In the fourth O site, O(4) is bonded in a distorted linear geometry to four equivalent La(1), one Ti(1), and one Ti(2) atom. In the fifth O site, O(5) is bonded in a distorted linear geometry to four equivalent La(1) and two equivalent Ti(2) atoms.
K2MgLa2Ti3O10 crystallizes in the tetragonal I-4m2 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 11-coordinate geometry to two equivalent Mg(1), two equivalent O(2), two equivalent O(3), and five equivalent O(1) atoms. Both K(1)-Mg(1) bond lengths are 2.65 Å. Both K(1)-O(2) bond lengths are 2.59 Å. Both K(1)-O(3) bond lengths are 2.65 Å. There is one shorter (2.83 Å) and four longer (2.89 Å) K(1)-O(1) bond lengths. In the second K site, K(1) is bonded in a 11-coordinate geometry to two equivalent Mg(1), two equivalent O(2), two equivalent O(3), and five equivalent O(1) atoms. Both K(1)-Mg(1) bond lengths are 2.65 Å. Both K(1)-O(2) bond lengths are 2.59 Å. Both K(1)-O(3) bond lengths are 2.65 Å. There is one shorter (2.83 Å) and four longer (2.89 Å) K(1)-O(1) bond lengths. Mg(1) is bonded in a 4-coordinate geometry to four equivalent K(1) and four equivalent O(1) atoms. All Mg(1)-O(1) bond lengths are 2.25 Å. La(1) is bonded to two equivalent O(2), two equivalent O(3), four equivalent O(4), and four equivalent O(5) atoms to form LaO12 cuboctahedra that share corners with eight equivalent La(1)O12 cuboctahedra, faces with five equivalent La(1)O12 cuboctahedra, faces with four equivalent Ti(1)O6 octahedra, and faces with four equivalent Ti(2)O6 octahedra. Both La(1)-O(2) bond lengths are 2.68 Å. Both La(1)-O(3) bond lengths are 2.63 Å. All La(1)-O(4) bond lengths are 2.80 Å. All La(1)-O(5) bond lengths are 2.83 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form TiO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, and faces with four equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-11°. The Ti(1)-O(1) bond length is 2.25 Å. The Ti(1)-O(4) bond length is 1.98 Å. Both Ti(1)-O(2) bond lengths are 1.99 Å. Both Ti(1)-O(3) bond lengths are 1.99 Å. In the second Ti site, Ti(2) is bonded to two equivalent O(4) and four equivalent O(5) atoms to form TiO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra, and faces with eight equivalent La(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. Both Ti(2)-O(4) bond lengths are 1.97 Å. All Ti(2)-O(5) bond lengths are 1.98 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to five equivalent K(1), two equivalent Mg(1), and one Ti(1) atom. In the second O site, O(2) is bonded to two equivalent K(1), two equivalent La(1), and two equivalent Ti(1) atoms to form a mixture of distorted face, corner, and edge-sharing OK2La2Ti2 octahedra. The corner-sharing octahedral tilt angles are 7°. In the third O site, O(3) is bonded to two equivalent K(1), two equivalent La(1), and two equivalent Ti(1) atoms to form a mixture of distorted face, corner, and edge-sharing OK2La2Ti2 octahedra. The corner-sharing octahedral tilt angles are 11°. In the fourth O site, O(4) is bonded in a distorted linear geometry to four equivalent La(1), one Ti(1), and one Ti(2) atom. In the fifth O site, O(5) is bonded in a distorted linear geometry to four equivalent La(1) and two equivalent Ti(2) atoms.