La4Bi2O9 crystallizes in the triclinic P1 space group. There are four inequivalent La sites. In the first La site, La(1) is bonded to one O(1), one O(2), one O(4), one O(6), one O(8), and one O(9) atom to form distorted LaO6 octahedra that share corners with two equivalent La(3)O5 trigonal bipyramids and  a cornercorner with one Bi(2)O4 trigonal pyramid. In the second La site, La(2) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom. In the third La site, La(3) is bonded to one O(3), one O(5), one O(7), one O(8), and one O(9) atom to form distorted LaO5 trigonal bipyramids that share corners with two equivalent La(1)O6 octahedra, corners with two equivalent Bi(2)O4 trigonal pyramids, and  an edgeedge with one Bi(2)O4 trigonal pyramid. The corner-sharing octahedral tilt angles range from 52-55°. In the fourth La site, La(4) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(7) atom. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(6), and one O(8) atom. In the second Bi site, Bi(2) is bonded to one O(3), one O(5), one O(7), and one O(9) atom to form BiO4 trigonal pyramids that share  a cornercorner with one La(1)O6 octahedra, corners with two equivalent La(3)O5 trigonal bipyramids, and  an edgeedge with one La(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 57°. There are nine inequivalent O sites. In the first O site, O(1) is bonded to one La(1), one La(2), one La(4), and one Bi(1) atom to form a mixture of corner and edge-sharing OLa3Bi tetrahedra. In the second O site, O(2) is bonded to one La(1), one La(2), one La(4), and one Bi(1) atom to form a mixture of corner and edge-sharing OLa3Bi tetrahedra. In the third O site, O(3) is bonded in a 3-coordinate geometry to one La(2), one La(3), and one Bi(2) atom. In the fourth O site, O(4) is bonded to one La(1), one La(2), one La(4), and one Bi(1) atom to form a mixture of corner and edge-sharing OLa3Bi tetrahedra. In the fifth O site, O(5) is bonded to one La(2), one La(3), one La(4), and one Bi(2) atom to form a mixture of distorted corner and edge-sharing OLa3Bi tetrahedra. In the sixth O site, O(6) is bonded to one La(1), one La(2), one La(4), and one Bi(1) atom to form a mixture of corner and edge-sharing OLa3Bi tetrahedra. In the seventh O site, O(7) is bonded to one La(2), one La(3), one La(4), and one Bi(2) atom to form a mixture of corner and edge-sharing OLa3Bi tetrahedra. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one La(1), one La(3), and one Bi(1) atom. In the ninth O site, O(9) is bonded in a trigonal planar geometry to one La(1), one La(3), and one Bi(2) atom.
La4Bi2O9 crystallizes in the triclinic P1 space group. There are four inequivalent La sites. In the first La site, La(1) is bonded to one O(1), one O(2), one O(4), one O(6), one O(8), and one O(9) atom to form distorted LaO6 octahedra that share corners with two equivalent La(3)O5 trigonal bipyramids and  a cornercorner with one Bi(2)O4 trigonal pyramid. The La(1)-O(1) bond length is 2.52 Å. The La(1)-O(2) bond length is 2.43 Å. The La(1)-O(4) bond length is 2.41 Å. The La(1)-O(6) bond length is 2.40 Å. The La(1)-O(8) bond length is 2.52 Å. The La(1)-O(9) bond length is 2.44 Å. In the second La site, La(2) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom. The La(2)-O(1) bond length is 2.46 Å. The La(2)-O(2) bond length is 2.38 Å. The La(2)-O(3) bond length is 2.62 Å. The La(2)-O(4) bond length is 2.47 Å. The La(2)-O(5) bond length is 2.72 Å. The La(2)-O(6) bond length is 2.52 Å. The La(2)-O(7) bond length is 2.42 Å. In the third La site, La(3) is bonded to one O(3), one O(5), one O(7), one O(8), and one O(9) atom to form distorted LaO5 trigonal bipyramids that share corners with two equivalent La(1)O6 octahedra, corners with two equivalent Bi(2)O4 trigonal pyramids, and  an edgeedge with one Bi(2)O4 trigonal pyramid. The corner-sharing octahedral tilt angles range from 52-55°. The La(3)-O(3) bond length is 2.29 Å. The La(3)-O(5) bond length is 2.38 Å. The La(3)-O(7) bond length is 2.52 Å. The La(3)-O(8) bond length is 2.34 Å. The La(3)-O(9) bond length is 2.43 Å. In the fourth La site, La(4) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(7) atom. The La(4)-O(1) bond length is 2.47 Å. The La(4)-O(2) bond length is 2.29 Å. The La(4)-O(4) bond length is 2.47 Å. The La(4)-O(5) bond length is 2.59 Å. The La(4)-O(6) bond length is 2.44 Å. The La(4)-O(7) bond length is 2.42 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(6), and one O(8) atom. The Bi(1)-O(1) bond length is 2.17 Å. The Bi(1)-O(2) bond length is 2.59 Å. The Bi(1)-O(4) bond length is 2.37 Å. The Bi(1)-O(6) bond length is 2.29 Å. The Bi(1)-O(8) bond length is 2.34 Å. In the second Bi site, Bi(2) is bonded to one O(3), one O(5), one O(7), and one O(9) atom to form BiO4 trigonal pyramids that share  a cornercorner with one La(1)O6 octahedra, corners with two equivalent La(3)O5 trigonal bipyramids, and  an edgeedge with one La(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 57°. The Bi(2)-O(3) bond length is 2.30 Å. The Bi(2)-O(5) bond length is 2.34 Å. The Bi(2)-O(7) bond length is 2.14 Å. The Bi(2)-O(9) bond length is 2.19 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded to one La(1), one La(2), one La(4), and one Bi(1) atom to form a mixture of corner and edge-sharing OLa3Bi tetrahedra. In the second O site, O(2) is bonded to one La(1), one La(2), one La(4), and one Bi(1) atom to form a mixture of corner and edge-sharing OLa3Bi tetrahedra. In the third O site, O(3) is bonded in a 3-coordinate geometry to one La(2), one La(3), and one Bi(2) atom. In the fourth O site, O(4) is bonded to one La(1), one La(2), one La(4), and one Bi(1) atom to form a mixture of corner and edge-sharing OLa3Bi tetrahedra. In the fifth O site, O(5) is bonded to one La(2), one La(3), one La(4), and one Bi(2) atom to form a mixture of distorted corner and edge-sharing OLa3Bi tetrahedra. In the sixth O site, O(6) is bonded to one La(1), one La(2), one La(4), and one Bi(1) atom to form a mixture of corner and edge-sharing OLa3Bi tetrahedra. In the seventh O site, O(7) is bonded to one La(2), one La(3), one La(4), and one Bi(2) atom to form a mixture of corner and edge-sharing OLa3Bi tetrahedra. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one La(1), one La(3), and one Bi(1) atom. In the ninth O site, O(9) is bonded in a trigonal planar geometry to one La(1), one La(3), and one Bi(2) atom.