Li2Sr3Nb4O13 crystallizes in the tetragonal I4/mmm space group. Li(1) is bonded in a 4-coordinate geometry to four equivalent O(4) atoms. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent O(2), four equivalent O(3), and four equivalent O(5) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, corners with four equivalent Sr(2)O12 cuboctahedra,  a faceface with one Sr(2)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Nb(1)O6 octahedra, and faces with four equivalent Nb(2)O6 octahedra. In the second Sr site, Sr(2) is bonded to four equivalent O(1) and eight equivalent O(3) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(2)O12 cuboctahedra, corners with eight equivalent Sr(1)O12 cuboctahedra, faces with two equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(2)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), and four 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, faces with four equivalent Sr(1)O12 cuboctahedra, and faces with four equivalent Sr(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second Nb site, Nb(2) is bonded to one O(2), one O(4), and four equivalent O(5) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra, corners with four equivalent Nb(2)O6 octahedra, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-13°. There are five inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Sr(2) and two equivalent Nb(1) atoms to form a mixture of distorted corner and edge-sharing OSr4Nb2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Sr(1), one Nb(1), and one Nb(2) atom. In the third O site, O(3) is bonded in a distorted linear geometry to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Nb(1) atoms. In the fourth O site, O(4) is bonded to four equivalent Li(1) and one Nb(2) atom to form a mixture of distorted corner and edge-sharing OLi4Nb trigonal bipyramids. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to two equivalent Sr(1) and two equivalent Nb(2) atoms.
Li2Sr3Nb4O13 crystallizes in the tetragonal I4/mmm space group. Li(1) is bonded in a 4-coordinate geometry to four equivalent O(4) atoms. All Li(1)-O(4) bond lengths are 2.10 Å. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent O(2), four equivalent O(3), and four equivalent O(5) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, corners with four equivalent Sr(2)O12 cuboctahedra,  a faceface with one Sr(2)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Nb(1)O6 octahedra, and faces with four equivalent Nb(2)O6 octahedra. All Sr(1)-O(2) bond lengths are 2.87 Å. All Sr(1)-O(3) bond lengths are 3.04 Å. All Sr(1)-O(5) bond lengths are 2.66 Å. In the second Sr site, Sr(2) is bonded to four equivalent O(1) and eight equivalent O(3) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(2)O12 cuboctahedra, corners with eight equivalent Sr(1)O12 cuboctahedra, faces with two equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(2)O12 cuboctahedra, and faces with eight equivalent Nb(1)O6 octahedra. All Sr(2)-O(1) bond lengths are 2.87 Å. All Sr(2)-O(3) bond lengths are 2.86 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), and four 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, faces with four equivalent Sr(1)O12 cuboctahedra, and faces with four equivalent Sr(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-2°. The Nb(1)-O(1) bond length is 2.06 Å. The Nb(1)-O(2) bond length is 2.02 Å. All Nb(1)-O(3) bond lengths are 2.03 Å. In the second Nb site, Nb(2) is bonded to one O(2), one O(4), and four equivalent O(5) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra, corners with four equivalent Nb(2)O6 octahedra, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-13°. The Nb(2)-O(2) bond length is 2.16 Å. The Nb(2)-O(4) bond length is 1.90 Å. All Nb(2)-O(5) bond lengths are 2.04 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Sr(2) and two equivalent Nb(1) atoms to form a mixture of distorted corner and edge-sharing OSr4Nb2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Sr(1), one Nb(1), and one Nb(2) atom. In the third O site, O(3) is bonded in a distorted linear geometry to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Nb(1) atoms. In the fourth O site, O(4) is bonded to four equivalent Li(1) and one Nb(2) atom to form a mixture of distorted corner and edge-sharing OLi4Nb trigonal bipyramids. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to two equivalent Sr(1) and two equivalent Nb(2) atoms.