Li4Sr3Nb6O20 crystallizes in the triclinic P1 space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to one O(12), one O(19), one O(4), one O(8), and one O(9) atom. In the second Li site, Li(2,3) is bonded in a 4-coordinate geometry to one O(12); one O(16,18); one O(19); one O(4); and one O(8) atom. In the third Li site, Li(4) is bonded in a 4-coordinate geometry to one O(12), one O(19), one O(20), one O(4), and one O(8) atom. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one O(10), one O(13), one O(14), one O(15), one O(2), one O(3), one O(5), one O(6), two equivalent O(11), and two equivalent O(7) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(3)O12 cuboctahedra, faces with two equivalent Nb(2)O6 octahedra, faces with two equivalent Nb(3)O6 octahedra, faces with two equivalent Nb(4)O6 octahedra, and faces with two equivalent Nb(5)O6 octahedra. In the second Sr site, Sr(2) is bonded in a 12-coordinate geometry to one O(13); one O(14); one O(2); one O(20); one O(5); one O(9); two equivalent O(1); two equivalent O(16,18); and two equivalent O(17) atoms. In the third Sr site, Sr(3) is bonded to one O(10), one O(13), one O(14), one O(15), one O(2), one O(3), one O(5), one O(6), two equivalent O(11), and two equivalent O(7) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(3)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, faces with two equivalent Nb(2)O6 octahedra, faces with two equivalent Nb(3)O6 octahedra, faces with two equivalent Nb(4)O6 octahedra, and faces with two equivalent Nb(5)O6 octahedra. There are six inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1); one O(20); one O(4); one O(9); and two equivalent O(16,18) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 0-11°. In the second Nb site, Nb(2) is bonded to one O(13), one O(14), one O(17), one O(2), one O(5), and one O(7) atom to form NbO6 octahedra that share  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(6)O6 octahedra, corners with four equivalent Nb(4)O6 octahedra, faces with two equivalent Sr(1)O12 cuboctahedra, and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-16°. In the third Nb site, Nb(3) is bonded to one O(10), one O(15), one O(3), one O(6), one O(7), and one O(8) atom to form NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra, corners with four equivalent Nb(5)O6 octahedra, faces with two equivalent Sr(1)O12 cuboctahedra, and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 1-12°. In the fourth Nb site, Nb(4) is bonded to one O(1), one O(11), one O(13), one O(14), one O(2), and one O(5) atom to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra, corners with four equivalent Nb(2)O6 octahedra, faces with two equivalent Sr(1)O12 cuboctahedra, and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-16°. In the fifth Nb site, Nb(5) is bonded to one O(10), one O(11), one O(12), one O(15), one O(3), and one O(6) atom to form NbO6 octahedra that share  a cornercorner with one Nb(4)O6 octahedra, corners with four equivalent Nb(3)O6 octahedra, faces with two equivalent Sr(1)O12 cuboctahedra, and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 1-12°. In the sixth Nb site, Nb(6) is bonded to one O(17); one O(19); one O(20); one O(9); and two equivalent O(16,18) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 0-11°. There are nineteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Sr(2), one Nb(1), and one Nb(4) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Nb(2), and one Nb(4) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(3), one Nb(3), and one Nb(5) atom. In the fourth O site, O(4) is bonded to one Li(1); one Li(4); two equivalent Li(2,3); and one Nb(1) atom to form a mixture of distorted edge and corner-sharing OLi4Nb trigonal bipyramids. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Nb(2), and one Nb(4) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(3), one Nb(3), and one Nb(5) atom. In the seventh O site, O(7) is bonded to two equivalent Sr(1), two equivalent Sr(3), one Nb(2), and one Nb(3) atom to form distorted OSr4Nb2 octahedra that share corners with four equivalent O(7)Sr4Nb2 octahedra,  a cornercorner with one O(8)Li4Nb trigonal bipyramid, and edges with four equivalent O(11)Sr4Nb2 octahedra. The corner-sharing octahedral tilt angles are 2°. In the eighth O site, O(8) is bonded to one Li(1); one Li(4); two equivalent Li(2,3); and one Nb(3) atom to form distorted OLi4Nb trigonal bipyramids that share  a cornercorner with one O(7)Sr4Nb2 octahedra, corners with four equivalent O(12)Li4Nb trigonal bipyramids, edges with two equivalent O(19)Li4Nb trigonal bipyramids, and edges with two equivalent O(4)Li4Nb trigonal bipyramids. The corner-sharing octahedral tilt angles are 1°. In the ninth O site, O(9) is bonded in a distorted see-saw-like geometry to one Li(1), one Sr(2), one Nb(1), and one Nb(6) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(3), one Nb(3), and one Nb(5) atom. In the eleventh O site, O(11) is bonded to two equivalent Sr(1), two equivalent Sr(3), one Nb(4), and one Nb(5) atom to form distorted OSr4Nb2 octahedra that share corners with four equivalent O(11)Sr4Nb2 octahedra,  a cornercorner with one O(12)Li4Nb trigonal bipyramid, and edges with four equivalent O(7)Sr4Nb2 octahedra. The corner-sharing octahedral tilt angles are 2°. In the twelfth O site, O(12) is bonded to one Li(1); one Li(4); two equivalent Li(2,3); and one Nb(5) atom to form distorted OLi4Nb trigonal bipyramids that share  a cornercorner with one O(11)Sr4Nb2 octahedra, corners with four equivalent O(8)Li4Nb trigonal bipyramids, edges with two equivalent O(19)Li4Nb trigonal bipyramids, and edges with two equivalent O(4)Li4Nb trigonal bipyramids. The corner-sharing octahedral tilt angles are 1°. In the thirteenth O site, O(13) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Nb(2), and one Nb(4) atom. In the fourteenth O site, O(14) is bonded in a distorted linear geometry to one Sr(1), one Sr(2), one Sr(3), one Nb(2), and one Nb(4) atom. In the fifteenth O site, O(15) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(3), one Nb(3), and one Nb(5) atom. In the sixteenth O site, O(16,18) is bonded in a distorted see-saw-like geometry to one Li(2,3); one Sr(2); one Nb(1); and one Nb(6) atom. In the seventeenth O site, O(17) is bonded in a 4-coordinate geometry to two equivalent Sr(2), one Nb(2), and one Nb(6) atom. In the eighteenth O site, O(19) is bonded to one Li(1); one Li(4); two equivalent Li(2,3); and one Nb(6) atom to form a mixture of distorted edge and corner-sharing OLi4Nb trigonal bipyramids. In the nineteenth O site, O(20) is bonded in a distorted see-saw-like geometry to one Li(4), one Sr(2), one Nb(1), and one Nb(6) atom.
Li4Sr3Nb6O20 crystallizes in the triclinic P1 space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to one O(12), one O(19), one O(4), one O(8), and one O(9) atom. The Li(1)-O(12) bond length is 2.09 Å. The Li(1)-O(19) bond length is 2.06 Å. The Li(1)-O(4) bond length is 2.06 Å. The Li(1)-O(8) bond length is 2.10 Å. The Li(1)-O(9) bond length is 2.57 Å. In the second Li site, Li(2,3) is bonded in a 4-coordinate geometry to one O(12); one O(16,18); one O(19); one O(4); and one O(8) atom. The Li(2,3)-O(12) bond length is 2.09 Å. The Li(2,3)-O(16,18) bond length is 2.56 Å. The Li(2,3)-O(19) bond length is 2.07 Å. The Li(2,3)-O(4) bond length is 2.06 Å. The Li(2,3)-O(8) bond length is 2.10 Å. In the third Li site, Li(4) is bonded in a 4-coordinate geometry to one O(12), one O(19), one O(20), one O(4), and one O(8) atom. The Li(4)-O(12) bond length is 2.10 Å. The Li(4)-O(19) bond length is 2.06 Å. The Li(4)-O(20) bond length is 2.57 Å. The Li(4)-O(4) bond length is 2.06 Å. The Li(4)-O(8) bond length is 2.10 Å. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one O(10), one O(13), one O(14), one O(15), one O(2), one O(3), one O(5), one O(6), two equivalent O(11), and two equivalent O(7) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(3)O12 cuboctahedra, faces with two equivalent Nb(2)O6 octahedra, faces with two equivalent Nb(3)O6 octahedra, faces with two equivalent Nb(4)O6 octahedra, and faces with two equivalent Nb(5)O6 octahedra. The Sr(1)-O(10) bond length is 2.76 Å. The Sr(1)-O(13) bond length is 2.69 Å. The Sr(1)-O(14) bond length is 2.81 Å. The Sr(1)-O(15) bond length is 2.75 Å. The Sr(1)-O(2) bond length is 2.96 Å. The Sr(1)-O(3) bond length is 2.77 Å. The Sr(1)-O(5) bond length is 2.69 Å. The Sr(1)-O(6) bond length is 2.76 Å. There is one shorter (2.81 Å) and one longer (2.86 Å) Sr(1)-O(11) bond length. There is one shorter (2.81 Å) and one longer (2.86 Å) Sr(1)-O(7) bond length. In the second Sr site, Sr(2) is bonded in a 12-coordinate geometry to one O(13); one O(14); one O(2); one O(20); one O(5); one O(9); two equivalent O(1); two equivalent O(16,18); and two equivalent O(17) atoms. The Sr(2)-O(13) bond length is 2.96 Å. The Sr(2)-O(14) bond length is 3.07 Å. The Sr(2)-O(2) bond length is 3.27 Å. The Sr(2)-O(20) bond length is 2.62 Å. The Sr(2)-O(5) bond length is 2.95 Å. The Sr(2)-O(9) bond length is 2.64 Å. There is one shorter (2.82 Å) and one longer (2.87 Å) Sr(2)-O(1) bond length. There is one shorter (2.63 Å) and one longer (2.64 Å) Sr(2)-O(16,18) bond length. There is one shorter (2.82 Å) and one longer (2.87 Å) Sr(2)-O(17) bond length. In the third Sr site, Sr(3) is bonded to one O(10), one O(13), one O(14), one O(15), one O(2), one O(3), one O(5), one O(6), two equivalent O(11), and two equivalent O(7) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(3)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, faces with two equivalent Nb(2)O6 octahedra, faces with two equivalent Nb(3)O6 octahedra, faces with two equivalent Nb(4)O6 octahedra, and faces with two equivalent Nb(5)O6 octahedra. The Sr(3)-O(10) bond length is 2.75 Å. The Sr(3)-O(13) bond length is 2.96 Å. The Sr(3)-O(14) bond length is 2.81 Å. The Sr(3)-O(15) bond length is 2.76 Å. The Sr(3)-O(2) bond length is 2.66 Å. The Sr(3)-O(3) bond length is 2.75 Å. The Sr(3)-O(5) bond length is 2.97 Å. The Sr(3)-O(6) bond length is 2.75 Å. There is one shorter (2.83 Å) and one longer (2.84 Å) Sr(3)-O(11) bond length. There is one shorter (2.83 Å) and one longer (2.84 Å) Sr(3)-O(7) bond length. There are six inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1); one O(20); one O(4); one O(9); and two equivalent O(16,18) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 0-11°. The Nb(1)-O(1) bond length is 2.22 Å. The Nb(1)-O(20) bond length is 2.01 Å. The Nb(1)-O(4) bond length is 1.90 Å. The Nb(1)-O(9) bond length is 2.01 Å. There is one shorter (2.00 Å) and one longer (2.02 Å) Nb(1)-O(16,18) bond length. In the second Nb site, Nb(2) is bonded to one O(13), one O(14), one O(17), one O(2), one O(5), and one O(7) atom to form NbO6 octahedra that share  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(6)O6 octahedra, corners with four equivalent Nb(4)O6 octahedra, faces with two equivalent Sr(1)O12 cuboctahedra, and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-16°. The Nb(2)-O(13) bond length is 2.05 Å. The Nb(2)-O(14) bond length is 2.02 Å. The Nb(2)-O(17) bond length is 1.90 Å. The Nb(2)-O(2) bond length is 2.01 Å. The Nb(2)-O(5) bond length is 1.99 Å. The Nb(2)-O(7) bond length is 2.11 Å. In the third Nb site, Nb(3) is bonded to one O(10), one O(15), one O(3), one O(6), one O(7), and one O(8) atom to form NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra, corners with four equivalent Nb(5)O6 octahedra, faces with two equivalent Sr(1)O12 cuboctahedra, and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 1-12°. The Nb(3)-O(10) bond length is 2.00 Å. The Nb(3)-O(15) bond length is 2.01 Å. The Nb(3)-O(3) bond length is 2.01 Å. The Nb(3)-O(6) bond length is 2.03 Å. The Nb(3)-O(7) bond length is 2.15 Å. The Nb(3)-O(8) bond length is 1.90 Å. In the fourth Nb site, Nb(4) is bonded to one O(1), one O(11), one O(13), one O(14), one O(2), and one O(5) atom to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra, corners with four equivalent Nb(2)O6 octahedra, faces with two equivalent Sr(1)O12 cuboctahedra, and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-16°. The Nb(4)-O(1) bond length is 1.90 Å. The Nb(4)-O(11) bond length is 2.11 Å. The Nb(4)-O(13) bond length is 1.99 Å. The Nb(4)-O(14) bond length is 2.02 Å. The Nb(4)-O(2) bond length is 2.01 Å. The Nb(4)-O(5) bond length is 2.05 Å. In the fifth Nb site, Nb(5) is bonded to one O(10), one O(11), one O(12), one O(15), one O(3), and one O(6) atom to form NbO6 octahedra that share  a cornercorner with one Nb(4)O6 octahedra, corners with four equivalent Nb(3)O6 octahedra, faces with two equivalent Sr(1)O12 cuboctahedra, and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 1-12°. The Nb(5)-O(10) bond length is 2.03 Å. The Nb(5)-O(11) bond length is 2.15 Å. The Nb(5)-O(12) bond length is 1.90 Å. The Nb(5)-O(15) bond length is 2.01 Å. The Nb(5)-O(3) bond length is 2.01 Å. The Nb(5)-O(6) bond length is 2.00 Å. In the sixth Nb site, Nb(6) is bonded to one O(17); one O(19); one O(20); one O(9); and two equivalent O(16,18) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 0-11°. The Nb(6)-O(17) bond length is 2.22 Å. The Nb(6)-O(19) bond length is 1.90 Å. The Nb(6)-O(20) bond length is 2.01 Å. The Nb(6)-O(9) bond length is 2.01 Å. There is one shorter (2.00 Å) and one longer (2.02 Å) Nb(6)-O(16,18) bond length. There are nineteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Sr(2), one Nb(1), and one Nb(4) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Nb(2), and one Nb(4) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(3), one Nb(3), and one Nb(5) atom. In the fourth O site, O(4) is bonded to one Li(1); one Li(4); two equivalent Li(2,3); and one Nb(1) atom to form a mixture of distorted edge and corner-sharing OLi4Nb trigonal bipyramids. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Nb(2), and one Nb(4) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(3), one Nb(3), and one Nb(5) atom. In the seventh O site, O(7) is bonded to two equivalent Sr(1), two equivalent Sr(3), one Nb(2), and one Nb(3) atom to form distorted OSr4Nb2 octahedra that share corners with four equivalent O(7)Sr4Nb2 octahedra,  a cornercorner with one O(8)Li4Nb trigonal bipyramid, and edges with four equivalent O(11)Sr4Nb2 octahedra. The corner-sharing octahedral tilt angles are 2°. In the eighth O site, O(8) is bonded to one Li(1); one Li(4); two equivalent Li(2,3); and one Nb(3) atom to form distorted OLi4Nb trigonal bipyramids that share  a cornercorner with one O(7)Sr4Nb2 octahedra, corners with four equivalent O(12)Li4Nb trigonal bipyramids, edges with two equivalent O(19)Li4Nb trigonal bipyramids, and edges with two equivalent O(4)Li4Nb trigonal bipyramids. The corner-sharing octahedral tilt angles are 1°. In the ninth O site, O(9) is bonded in a distorted see-saw-like geometry to one Li(1), one Sr(2), one Nb(1), and one Nb(6) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(3), one Nb(3), and one Nb(5) atom. In the eleventh O site, O(11) is bonded to two equivalent Sr(1), two equivalent Sr(3), one Nb(4), and one Nb(5) atom to form distorted OSr4Nb2 octahedra that share corners with four equivalent O(11)Sr4Nb2 octahedra,  a cornercorner with one O(12)Li4Nb trigonal bipyramid, and edges with four equivalent O(7)Sr4Nb2 octahedra. The corner-sharing octahedral tilt angles are 2°. In the twelfth O site, O(12) is bonded to one Li(1); one Li(4); two equivalent Li(2,3); and one Nb(5) atom to form distorted OLi4Nb trigonal bipyramids that share  a cornercorner with one O(11)Sr4Nb2 octahedra, corners with four equivalent O(8)Li4Nb trigonal bipyramids, edges with two equivalent O(19)Li4Nb trigonal bipyramids, and edges with two equivalent O(4)Li4Nb trigonal bipyramids. The corner-sharing octahedral tilt angles are 1°. In the thirteenth O site, O(13) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Nb(2), and one Nb(4) atom. In the fourteenth O site, O(14) is bonded in a distorted linear geometry to one Sr(1), one Sr(2), one Sr(3), one Nb(2), and one Nb(4) atom. In the fifteenth O site, O(15) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(3), one Nb(3), and one Nb(5) atom. In the sixteenth O site, O(16,18) is bonded in a distorted see-saw-like geometry to one Li(2,3); one Sr(2); one Nb(1); and one Nb(6) atom. In the seventeenth O site, O(17) is bonded in a 4-coordinate geometry to two equivalent Sr(2), one Nb(2), and one Nb(6) atom. In the eighteenth O site, O(19) is bonded to one Li(1); one Li(4); two equivalent Li(2,3); and one Nb(6) atom to form a mixture of distorted edge and corner-sharing OLi4Nb trigonal bipyramids. In the nineteenth O site, O(20) is bonded in a distorted see-saw-like geometry to one Li(4), one Sr(2), one Nb(1), and one Nb(6) atom.