Li4Sr3Nb6O20 crystallizes in the orthorhombic Amm2 space group. Li(1) is bonded in a 4-coordinate geometry to one O(10); one O(11); one O(5); and two equivalent O(8,9) atoms. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent O(1,2); four equivalent O(5); and four equivalent O(7) atoms to form distorted SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra; corners with four equivalent Sr(3)O12 cuboctahedra;  a faceface with one Sr(2)O12 cuboctahedra; faces with two equivalent Nb(5)O6 octahedra; faces with two equivalent Nb(6)O6 octahedra; and faces with four equivalent Nb(1,2)O6 octahedra. In the second Sr site, Sr(2) is bonded to four equivalent O(3,4); four equivalent O(6); and four equivalent O(7) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(2)O12 cuboctahedra,  a faceface with one Sr(1)O12 cuboctahedra, faces with four equivalent Sr(3)O12 cuboctahedra, faces with two equivalent Nb(3)O6 octahedra, faces with two equivalent Nb(4)O6 octahedra, faces with two equivalent Nb(5)O6 octahedra, and faces with two equivalent Nb(6)O6 octahedra. In the third Sr site, Sr(3) is bonded to four equivalent O(3,4); four equivalent O(6); and four equivalent O(7) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, corners with four equivalent Sr(3)O12 cuboctahedra, faces with four equivalent Sr(2)O12 cuboctahedra, faces with two equivalent Nb(3)O6 octahedra, faces with two equivalent Nb(4)O6 octahedra, faces with two equivalent Nb(5)O6 octahedra, and faces with two equivalent Nb(6)O6 octahedra. There are five inequivalent Nb sites. In the first Nb site, Nb(1,2) is bonded to one O(1,2); one O(8,9); and four equivalent O(5) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(6)O6 octahedra; corners with four equivalent Nb(1,2)O6 octahedra; and faces with two equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-11°. In the second Nb site, Nb(3) is bonded to one O(10); one O(3,4); and four equivalent O(6) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(5)O6 octahedra, corners with four equivalent Nb(4)O6 octahedra, faces with two equivalent Sr(2)O12 cuboctahedra, and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-12°. In the third Nb site, Nb(4) is bonded to one O(11); one O(3,4); and four equivalent O(6) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(6)O6 octahedra, corners with four equivalent Nb(3)O6 octahedra, faces with two equivalent Sr(2)O12 cuboctahedra, and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-12°. In the fourth Nb site, Nb(5) is bonded to one O(1,2); one O(3,4); and four equivalent O(7) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(1,2)O6 octahedra;  a cornercorner with one Nb(3)O6 octahedra; corners with four equivalent Nb(6)O6 octahedra; faces with two equivalent Sr(1)O12 cuboctahedra; faces with two equivalent Sr(2)O12 cuboctahedra; and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-11°. In the fifth Nb site, Nb(6) is bonded to one O(1,2); one O(3,4); and four equivalent O(7) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(1,2)O6 octahedra;  a cornercorner with one Nb(4)O6 octahedra; corners with four equivalent Nb(5)O6 octahedra; faces with two equivalent Sr(1)O12 cuboctahedra; faces with two equivalent Sr(2)O12 cuboctahedra; and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-11°. There are eight inequivalent O sites. In the first O site, O(6) is bonded in a 2-coordinate geometry to one Sr(2), one Sr(3), one Nb(3), and one Nb(4) atom. In the second O site, O(7) is bonded in a distorted linear geometry to one Sr(1), one Sr(2), one Sr(3), one Nb(5), and one Nb(6) atom. In the third O site, O(8,9) is bonded to four equivalent Li(1) and one Nb(1,2) atom to form a mixture of distorted corner and edge-sharing OLi4Nb trigonal bipyramids. In the fourth O site, O(10) is bonded to four equivalent Li(1) and one Nb(3) atom to form distorted OLi4Nb trigonal bipyramids that share  a cornercorner with one O(3,4)Sr4Nb2 octahedra; corners with four equivalent O(11)Li4Nb trigonal bipyramids; and edges with four equivalent O(8,9)Li4Nb trigonal bipyramids. The corner-sharing octahedra are not tilted. In the fifth O site, O(11) is bonded to four equivalent Li(1) and one Nb(4) atom to form distorted OLi4Nb trigonal bipyramids that share  a cornercorner with one O(3,4)Sr4Nb2 octahedra; corners with four equivalent O(10)Li4Nb trigonal bipyramids; and edges with four equivalent O(8,9)Li4Nb trigonal bipyramids. The corner-sharing octahedra are not tilted. In the sixth O site, O(1,2) is bonded in a 4-coordinate geometry to two equivalent Sr(1); one Nb(1,2); and one Nb(6) atom. In the seventh O site, O(3,4) is bonded to two equivalent Sr(2), two equivalent Sr(3), one Nb(3), and one Nb(5) atom to form distorted OSr4Nb2 octahedra that share corners with four equivalent O(3,4)Sr4Nb2 octahedra;  a cornercorner with one O(10)Li4Nb trigonal bipyramid; and edges with four equivalent O(3,4)Sr4Nb2 octahedra. The corner-sharing octahedral tilt angles are 1°. In the eighth O site, O(5) is bonded in a 4-coordinate geometry to one Li(1); one Sr(1); and two equivalent Nb(1,2) atoms.
Li4Sr3Nb6O20 crystallizes in the orthorhombic Amm2 space group. Li(1) is bonded in a 4-coordinate geometry to one O(10); one O(11); one O(5); and two equivalent O(8,9) atoms. The Li(1)-O(10) bond length is 2.09 Å. The Li(1)-O(11) bond length is 2.10 Å. The Li(1)-O(5) bond length is 2.61 Å. Both Li(1)-O(8,9) bond lengths are 2.07 Å. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent O(1,2); four equivalent O(5); and four equivalent O(7) atoms to form distorted SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra; corners with four equivalent Sr(3)O12 cuboctahedra;  a faceface with one Sr(2)O12 cuboctahedra; faces with two equivalent Nb(5)O6 octahedra; faces with two equivalent Nb(6)O6 octahedra; and faces with four equivalent Nb(1,2)O6 octahedra. All Sr(1)-O(1,2) bond lengths are 2.84 Å. All Sr(1)-O(5) bond lengths are 2.63 Å. All Sr(1)-O(7) bond lengths are 3.05 Å. In the second Sr site, Sr(2) is bonded to four equivalent O(3,4); four equivalent O(6); and four equivalent O(7) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(2)O12 cuboctahedra,  a faceface with one Sr(1)O12 cuboctahedra, faces with four equivalent Sr(3)O12 cuboctahedra, faces with two equivalent Nb(3)O6 octahedra, faces with two equivalent Nb(4)O6 octahedra, faces with two equivalent Nb(5)O6 octahedra, and faces with two equivalent Nb(6)O6 octahedra. All Sr(2)-O(3,4) bond lengths are 2.83 Å. All Sr(2)-O(6) bond lengths are 2.76 Å. All Sr(2)-O(7) bond lengths are 2.77 Å. In the third Sr site, Sr(3) is bonded to four equivalent O(3,4); four equivalent O(6); and four equivalent O(7) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, corners with four equivalent Sr(3)O12 cuboctahedra, faces with four equivalent Sr(2)O12 cuboctahedra, faces with two equivalent Nb(3)O6 octahedra, faces with two equivalent Nb(4)O6 octahedra, faces with two equivalent Nb(5)O6 octahedra, and faces with two equivalent Nb(6)O6 octahedra. All Sr(3)-O(3,4) bond lengths are 2.83 Å. All Sr(3)-O(6) bond lengths are 2.77 Å. All Sr(3)-O(7) bond lengths are 2.83 Å. There are five inequivalent Nb sites. In the first Nb site, Nb(1,2) is bonded to one O(1,2); one O(8,9); and four equivalent O(5) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(6)O6 octahedra; corners with four equivalent Nb(1,2)O6 octahedra; and faces with two equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-11°. The Nb(1,2)-O(1,2) bond length is 2.22 Å. The Nb(1,2)-O(8,9) bond length is 1.89 Å. All Nb(1,2)-O(5) bond lengths are 2.01 Å. In the second Nb site, Nb(3) is bonded to one O(10); one O(3,4); and four equivalent O(6) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(5)O6 octahedra, corners with four equivalent Nb(4)O6 octahedra, faces with two equivalent Sr(2)O12 cuboctahedra, and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-12°. The Nb(3)-O(10) bond length is 1.90 Å. The Nb(3)-O(3,4) bond length is 2.15 Å. All Nb(3)-O(6) bond lengths are 2.01 Å. In the third Nb site, Nb(4) is bonded to one O(11); one O(3,4); and four equivalent O(6) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(6)O6 octahedra, corners with four equivalent Nb(3)O6 octahedra, faces with two equivalent Sr(2)O12 cuboctahedra, and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-12°. The Nb(4)-O(11) bond length is 1.90 Å. The Nb(4)-O(3,4) bond length is 2.15 Å. All Nb(4)-O(6) bond lengths are 2.01 Å. In the fourth Nb site, Nb(5) is bonded to one O(1,2); one O(3,4); and four equivalent O(7) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(1,2)O6 octahedra;  a cornercorner with one Nb(3)O6 octahedra; corners with four equivalent Nb(6)O6 octahedra; faces with two equivalent Sr(1)O12 cuboctahedra; faces with two equivalent Sr(2)O12 cuboctahedra; and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-11°. The Nb(5)-O(1,2) bond length is 1.89 Å. The Nb(5)-O(3,4) bond length is 2.12 Å. All Nb(5)-O(7) bond lengths are 2.01 Å. In the fifth Nb site, Nb(6) is bonded to one O(1,2); one O(3,4); and four equivalent O(7) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(1,2)O6 octahedra;  a cornercorner with one Nb(4)O6 octahedra; corners with four equivalent Nb(5)O6 octahedra; faces with two equivalent Sr(1)O12 cuboctahedra; faces with two equivalent Sr(2)O12 cuboctahedra; and faces with two equivalent Sr(3)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-11°. The Nb(6)-O(1,2) bond length is 1.89 Å. The Nb(6)-O(3,4) bond length is 2.12 Å. All Nb(6)-O(7) bond lengths are 2.01 Å. There are eight inequivalent O sites. In the first O site, O(6) is bonded in a 2-coordinate geometry to one Sr(2), one Sr(3), one Nb(3), and one Nb(4) atom. In the second O site, O(7) is bonded in a distorted linear geometry to one Sr(1), one Sr(2), one Sr(3), one Nb(5), and one Nb(6) atom. In the third O site, O(8,9) is bonded to four equivalent Li(1) and one Nb(1,2) atom to form a mixture of distorted corner and edge-sharing OLi4Nb trigonal bipyramids. In the fourth O site, O(10) is bonded to four equivalent Li(1) and one Nb(3) atom to form distorted OLi4Nb trigonal bipyramids that share  a cornercorner with one O(3,4)Sr4Nb2 octahedra; corners with four equivalent O(11)Li4Nb trigonal bipyramids; and edges with four equivalent O(8,9)Li4Nb trigonal bipyramids. The corner-sharing octahedra are not tilted. In the fifth O site, O(11) is bonded to four equivalent Li(1) and one Nb(4) atom to form distorted OLi4Nb trigonal bipyramids that share  a cornercorner with one O(3,4)Sr4Nb2 octahedra; corners with four equivalent O(10)Li4Nb trigonal bipyramids; and edges with four equivalent O(8,9)Li4Nb trigonal bipyramids. The corner-sharing octahedra are not tilted. In the sixth O site, O(1,2) is bonded in a 4-coordinate geometry to two equivalent Sr(1); one Nb(1,2); and one Nb(6) atom. In the seventh O site, O(3,4) is bonded to two equivalent Sr(2), two equivalent Sr(3), one Nb(3), and one Nb(5) atom to form distorted OSr4Nb2 octahedra that share corners with four equivalent O(3,4)Sr4Nb2 octahedra;  a cornercorner with one O(10)Li4Nb trigonal bipyramid; and edges with four equivalent O(3,4)Sr4Nb2 octahedra. The corner-sharing octahedral tilt angles are 1°. In the eighth O site, O(5) is bonded in a 4-coordinate geometry to one Li(1); one Sr(1); and two equivalent Nb(1,2) atoms.