La3NbO7 crystallizes in the orthorhombic Pnma space group. There are two inequivalent La sites. In the first La site, La(1) is bonded to one O(4), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted LaO7 pentagonal bipyramids that share corners with two equivalent Nb(1)O6 octahedra, corners with three equivalent La(1)O7 pentagonal bipyramids, edges with two equivalent Nb(1)O6 octahedra, and edges with two equivalent La(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 31-42°. In the second La site, La(2) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. Nb(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent La(1)O7 pentagonal bipyramids, and edges with four equivalent La(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 32°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent La(1) and two equivalent La(2) atoms to form OLa4 tetrahedra that share corners with four equivalent O(2)La3Nb tetrahedra, corners with six equivalent O(1)La4 tetrahedra,  an edgeedge with one O(1)La4 tetrahedra, and edges with two equivalent O(2)La3Nb tetrahedra. In the second O site, O(2) is bonded to one La(2), two equivalent La(1), and one Nb(1) atom to form distorted OLa3Nb tetrahedra that share corners with four equivalent O(1)La4 tetrahedra, edges with two equivalent O(2)La3Nb tetrahedra, and edges with two equivalent O(1)La4 tetrahedra. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent La(1) and one Nb(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent La(1) and two equivalent Nb(1) atoms.
La3NbO7 crystallizes in the orthorhombic Pnma space group. There are two inequivalent La sites. In the first La site, La(1) is bonded to one O(4), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted LaO7 pentagonal bipyramids that share corners with two equivalent Nb(1)O6 octahedra, corners with three equivalent La(1)O7 pentagonal bipyramids, edges with two equivalent Nb(1)O6 octahedra, and edges with two equivalent La(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 31-42°. The La(1)-O(4) bond length is 2.72 Å. Both La(1)-O(1) bond lengths are 2.36 Å. There is one shorter (2.49 Å) and one longer (2.50 Å) La(1)-O(2) bond length. There is one shorter (2.50 Å) and one longer (2.52 Å) La(1)-O(3) bond length. In the second La site, La(2) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. Both La(2)-O(2) bond lengths are 2.49 Å. There are two shorter (2.45 Å) and two longer (2.46 Å) La(2)-O(1) bond lengths. Nb(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent La(1)O7 pentagonal bipyramids, and edges with four equivalent La(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 32°. Both Nb(1)-O(2) bond lengths are 2.07 Å. Both Nb(1)-O(3) bond lengths are 1.96 Å. There is one shorter (1.95 Å) and one longer (2.10 Å) Nb(1)-O(4) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent La(1) and two equivalent La(2) atoms to form OLa4 tetrahedra that share corners with four equivalent O(2)La3Nb tetrahedra, corners with six equivalent O(1)La4 tetrahedra,  an edgeedge with one O(1)La4 tetrahedra, and edges with two equivalent O(2)La3Nb tetrahedra. In the second O site, O(2) is bonded to one La(2), two equivalent La(1), and one Nb(1) atom to form distorted OLa3Nb tetrahedra that share corners with four equivalent O(1)La4 tetrahedra, edges with two equivalent O(2)La3Nb tetrahedra, and edges with two equivalent O(1)La4 tetrahedra. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent La(1) and one Nb(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent La(1) and two equivalent Nb(1) atoms.