Cs3LaO3 crystallizes in the monoclinic C2/m space group. There are three inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 5-coordinate geometry to one O(1) and four equivalent O(2) atoms. In the second Cs site, Cs(2) is bonded in a 4-coordinate geometry to four equivalent O(2) atoms. In the third Cs site, Cs(3) is bonded in a 4-coordinate geometry to four equivalent O(2) atoms. La(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form edge-sharing LaO4 tetrahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Cs(1) and two equivalent La(1) atoms. In the second O site, O(2) is bonded in a 7-coordinate geometry to two equivalent Cs(1), two equivalent Cs(2), two equivalent Cs(3), and one La(1) atom.
Cs3LaO3 crystallizes in the monoclinic C2/m space group. There are three inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 5-coordinate geometry to one O(1) and four equivalent O(2) atoms. The Cs(1)-O(1) bond length is 2.81 Å. There are two shorter (3.28 Å) and two longer (3.47 Å) Cs(1)-O(2) bond lengths. In the second Cs site, Cs(2) is bonded in a 4-coordinate geometry to four equivalent O(2) atoms. There are two shorter (2.94 Å) and two longer (3.51 Å) Cs(2)-O(2) bond lengths. In the third Cs site, Cs(3) is bonded in a 4-coordinate geometry to four equivalent O(2) atoms. There are two shorter (3.10 Å) and two longer (3.44 Å) Cs(3)-O(2) bond lengths. La(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form edge-sharing LaO4 tetrahedra. There is one shorter (2.32 Å) and one longer (2.34 Å) La(1)-O(1) bond length. Both La(1)-O(2) bond lengths are 2.26 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Cs(1) and two equivalent La(1) atoms. In the second O site, O(2) is bonded in a 7-coordinate geometry to two equivalent Cs(1), two equivalent Cs(2), two equivalent Cs(3), and one La(1) atom.