(Li)2LaNb6O18 crystallizes in the orthorhombic Pmmm space group. The structure consists of two 7439-93-2 atoms inside a LaNb6O18 framework. In the LaNb6O18 framework, La(1) is bonded to four equivalent O(2), four equivalent O(3), and four equivalent O(7) atoms to form LaO12 cuboctahedra that share faces with two equivalent La(1)O12 cuboctahedra and faces with eight equivalent Nb(1)O6 octahedra. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(4), one O(7), and two equivalent O(3) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra, corners with five equivalent Nb(1)O6 octahedra, and faces with two equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 5-16°. In the second Nb site, Nb(2) is bonded to one O(6), one O(8), two equivalent O(4), and two equivalent O(5) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 0-12°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent La(1) and two equivalent Nb(1) atoms. In the third O site, O(3) is bonded in a 3-coordinate geometry to one La(1) and two equivalent Nb(1) atoms. In the fourth O site, O(4) is bonded in a linear geometry to one Nb(1) and one Nb(2) atom. In the fifth O site, O(5) is bonded in a linear geometry to two equivalent Nb(2) atoms. In the sixth O site, O(6) is bonded in a linear geometry to two equivalent Nb(2) atoms. In the seventh O site, O(7) is bonded to two equivalent La(1) and two equivalent Nb(1) atoms to form a mixture of distorted corner and edge-sharing OLa2Nb2 trigonal pyramids. In the eighth O site, O(8) is bonded in a linear geometry to two equivalent Nb(2) atoms.
(Li)2LaNb6O18 crystallizes in the orthorhombic Pmmm space group. The structure consists of two 7439-93-2 atoms inside a LaNb6O18 framework. In the LaNb6O18 framework, La(1) is bonded to four equivalent O(2), four equivalent O(3), and four equivalent O(7) atoms to form LaO12 cuboctahedra that share faces with two equivalent La(1)O12 cuboctahedra and faces with eight equivalent Nb(1)O6 octahedra. All La(1)-O(2) bond lengths are 2.75 Å. All La(1)-O(3) bond lengths are 2.64 Å. All La(1)-O(7) bond lengths are 2.67 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(4), one O(7), and two equivalent O(3) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra, corners with five equivalent Nb(1)O6 octahedra, and faces with two equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 5-16°. The Nb(1)-O(1) bond length is 1.94 Å. The Nb(1)-O(2) bond length is 2.07 Å. The Nb(1)-O(4) bond length is 1.94 Å. The Nb(1)-O(7) bond length is 2.07 Å. Both Nb(1)-O(3) bond lengths are 2.00 Å. In the second Nb site, Nb(2) is bonded to one O(6), one O(8), two equivalent O(4), and two equivalent O(5) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 0-12°. The Nb(2)-O(6) bond length is 2.04 Å. The Nb(2)-O(8) bond length is 1.96 Å. Both Nb(2)-O(4) bond lengths are 2.02 Å. Both Nb(2)-O(5) bond lengths are 1.99 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent La(1) and two equivalent Nb(1) atoms. In the third O site, O(3) is bonded in a 3-coordinate geometry to one La(1) and two equivalent Nb(1) atoms. In the fourth O site, O(4) is bonded in a linear geometry to one Nb(1) and one Nb(2) atom. In the fifth O site, O(5) is bonded in a linear geometry to two equivalent Nb(2) atoms. In the sixth O site, O(6) is bonded in a linear geometry to two equivalent Nb(2) atoms. In the seventh O site, O(7) is bonded to two equivalent La(1) and two equivalent Nb(1) atoms to form a mixture of distorted corner and edge-sharing OLa2Nb2 trigonal pyramids. In the eighth O site, O(8) is bonded in a linear geometry to two equivalent Nb(2) atoms.