Li2Nb(PO4)2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), two equivalent O(2), and two equivalent O(6) atoms. In the second Li site, Li(2) is bonded to one O(6), one O(7), one O(8), and two equivalent O(4) atoms to form distorted LiO5 trigonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, edges with two equivalent Nb(1)O6 octahedra, and  an edgeedge with one Li(2)O5 trigonal bipyramid. Nb(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form distorted NbO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and edges with two equivalent Li(2)O5 trigonal bipyramids. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with three equivalent Nb(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with two equivalent Li(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 48-57°. In the second P site, P(2) is bonded to one O(3), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Nb(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with three equivalent Li(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 40-52°. There are eight inequivalent O sites. In the first O site, O(7) is bonded in a 3-coordinate geometry to one Li(2), one Nb(1), and one P(2) atom. In the second O site, O(8) is bonded in a 3-coordinate geometry to one Li(2), one Nb(1), and one P(2) atom. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Li(1), one Nb(1), and one P(1) atom. In the fourth O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Li(1) and one Nb(1) atom. In the fifth O site, O(3) is bonded in a 3-coordinate geometry to one Li(1), one P(1), and one P(2) atom. In the sixth O site, O(4) is bonded to two equivalent Li(2), one Nb(1), and one P(1) atom to form distorted edge-sharing OLi2NbP tetrahedra. In the seventh O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Nb(1) and one P(1) atom. In the eighth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Li(2), two equivalent Li(1), and one P(2) atom.
Li2Nb(PO4)2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), two equivalent O(2), and two equivalent O(6) atoms. The Li(1)-O(1) bond length is 2.56 Å. The Li(1)-O(3) bond length is 2.48 Å. There is one shorter (2.09 Å) and one longer (2.21 Å) Li(1)-O(2) bond length. There is one shorter (2.05 Å) and one longer (2.61 Å) Li(1)-O(6) bond length. In the second Li site, Li(2) is bonded to one O(6), one O(7), one O(8), and two equivalent O(4) atoms to form distorted LiO5 trigonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, edges with two equivalent Nb(1)O6 octahedra, and  an edgeedge with one Li(2)O5 trigonal bipyramid. The Li(2)-O(6) bond length is 1.98 Å. The Li(2)-O(7) bond length is 2.10 Å. The Li(2)-O(8) bond length is 2.46 Å. There is one shorter (2.19 Å) and one longer (2.34 Å) Li(2)-O(4) bond length. Nb(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form distorted NbO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and edges with two equivalent Li(2)O5 trigonal bipyramids. The Nb(1)-O(1) bond length is 2.22 Å. The Nb(1)-O(2) bond length is 1.79 Å. The Nb(1)-O(4) bond length is 2.21 Å. The Nb(1)-O(5) bond length is 2.11 Å. The Nb(1)-O(7) bond length is 2.37 Å. The Nb(1)-O(8) bond length is 2.12 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with three equivalent Nb(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with two equivalent Li(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 48-57°. The P(1)-O(1) bond length is 1.53 Å. The P(1)-O(3) bond length is 1.61 Å. The P(1)-O(4) bond length is 1.55 Å. The P(1)-O(5) bond length is 1.53 Å. In the second P site, P(2) is bonded to one O(3), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Nb(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with three equivalent Li(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 40-52°. The P(2)-O(3) bond length is 1.64 Å. The P(2)-O(6) bond length is 1.52 Å. The P(2)-O(7) bond length is 1.53 Å. The P(2)-O(8) bond length is 1.54 Å. There are eight inequivalent O sites. In the first O site, O(7) is bonded in a 3-coordinate geometry to one Li(2), one Nb(1), and one P(2) atom. In the second O site, O(8) is bonded in a 3-coordinate geometry to one Li(2), one Nb(1), and one P(2) atom. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Li(1), one Nb(1), and one P(1) atom. In the fourth O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Li(1) and one Nb(1) atom. In the fifth O site, O(3) is bonded in a 3-coordinate geometry to one Li(1), one P(1), and one P(2) atom. In the sixth O site, O(4) is bonded to two equivalent Li(2), one Nb(1), and one P(1) atom to form distorted edge-sharing OLi2NbP tetrahedra. In the seventh O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Nb(1) and one P(1) atom. In the eighth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Li(2), two equivalent Li(1), and one P(2) atom.