La2HfO5 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(1), one O(4), one O(5), two equivalent O(2), and two equivalent O(3) atoms to form distorted LaO7 hexagonal pyramids that share corners with three equivalent Hf(1)O5 trigonal bipyramids, edges with two equivalent La(1)O7 hexagonal pyramids, and edges with two equivalent Hf(1)O5 trigonal bipyramids. In the second La site, La(2) is bonded in a 7-coordinate geometry to one O(3), one O(5), two equivalent O(4), and three equivalent O(1) atoms. Hf(1) is bonded to one O(2), one O(3), one O(4), and two equivalent O(5) atoms to form distorted HfO5 trigonal bipyramids that share corners with three equivalent La(1)O7 hexagonal pyramids, corners with two equivalent Hf(1)O5 trigonal bipyramids, and edges with two equivalent La(1)O7 hexagonal pyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded to one La(1) and three equivalent La(2) atoms to form OLa4 tetrahedra that share corners with two equivalent O(5)La2Hf2 tetrahedra, corners with two equivalent O(1)La4 tetrahedra, corners with five equivalent O(3)La3Hf tetrahedra, corners with five equivalent O(4)La3Hf tetrahedra,  an edgeedge with one O(5)La2Hf2 tetrahedra,  an edgeedge with one O(4)La3Hf tetrahedra, and edges with two equivalent O(1)La4 tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent La(1) and one Hf(1) atom. In the third O site, O(3) is bonded to one La(2), two equivalent La(1), and one Hf(1) atom to form OLa3Hf tetrahedra that share  a cornercorner with one O(5)La2Hf2 tetrahedra,  a cornercorner with one O(4)La3Hf tetrahedra, corners with two equivalent O(3)La3Hf tetrahedra, corners with five equivalent O(1)La4 tetrahedra, edges with two equivalent O(5)La2Hf2 tetrahedra, and edges with two equivalent O(4)La3Hf tetrahedra. In the fourth O site, O(4) is bonded to one La(1), two equivalent La(2), and one Hf(1) atom to form OLa3Hf tetrahedra that share  a cornercorner with one O(5)La2Hf2 tetrahedra,  a cornercorner with one O(3)La3Hf tetrahedra, corners with two equivalent O(4)La3Hf tetrahedra, corners with five equivalent O(1)La4 tetrahedra,  an edgeedge with one O(1)La4 tetrahedra, edges with two equivalent O(5)La2Hf2 tetrahedra, and edges with two equivalent O(3)La3Hf tetrahedra. In the fifth O site, O(5) is bonded to one La(1), one La(2), and two equivalent Hf(1) atoms to form distorted OLa2Hf2 tetrahedra that share  a cornercorner with one O(3)La3Hf tetrahedra,  a cornercorner with one O(4)La3Hf tetrahedra, corners with two equivalent O(5)La2Hf2 tetrahedra, corners with two equivalent O(1)La4 tetrahedra,  an edgeedge with one O(1)La4 tetrahedra, edges with two equivalent O(3)La3Hf tetrahedra, and edges with two equivalent O(4)La3Hf tetrahedra.
La2HfO5 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(1), one O(4), one O(5), two equivalent O(2), and two equivalent O(3) atoms to form distorted LaO7 hexagonal pyramids that share corners with three equivalent Hf(1)O5 trigonal bipyramids, edges with two equivalent La(1)O7 hexagonal pyramids, and edges with two equivalent Hf(1)O5 trigonal bipyramids. The La(1)-O(1) bond length is 2.47 Å. The La(1)-O(4) bond length is 2.54 Å. The La(1)-O(5) bond length is 2.59 Å. Both La(1)-O(2) bond lengths are 2.52 Å. Both La(1)-O(3) bond lengths are 2.42 Å. In the second La site, La(2) is bonded in a 7-coordinate geometry to one O(3), one O(5), two equivalent O(4), and three equivalent O(1) atoms. The La(2)-O(3) bond length is 2.54 Å. The La(2)-O(5) bond length is 2.58 Å. Both La(2)-O(4) bond lengths are 2.53 Å. There are two shorter (2.48 Å) and one longer (2.50 Å) La(2)-O(1) bond length. Hf(1) is bonded to one O(2), one O(3), one O(4), and two equivalent O(5) atoms to form distorted HfO5 trigonal bipyramids that share corners with three equivalent La(1)O7 hexagonal pyramids, corners with two equivalent Hf(1)O5 trigonal bipyramids, and edges with two equivalent La(1)O7 hexagonal pyramids. The Hf(1)-O(2) bond length is 1.94 Å. The Hf(1)-O(3) bond length is 2.02 Å. The Hf(1)-O(4) bond length is 2.03 Å. Both Hf(1)-O(5) bond lengths are 2.08 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to one La(1) and three equivalent La(2) atoms to form OLa4 tetrahedra that share corners with two equivalent O(5)La2Hf2 tetrahedra, corners with two equivalent O(1)La4 tetrahedra, corners with five equivalent O(3)La3Hf tetrahedra, corners with five equivalent O(4)La3Hf tetrahedra,  an edgeedge with one O(5)La2Hf2 tetrahedra,  an edgeedge with one O(4)La3Hf tetrahedra, and edges with two equivalent O(1)La4 tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent La(1) and one Hf(1) atom. In the third O site, O(3) is bonded to one La(2), two equivalent La(1), and one Hf(1) atom to form OLa3Hf tetrahedra that share  a cornercorner with one O(5)La2Hf2 tetrahedra,  a cornercorner with one O(4)La3Hf tetrahedra, corners with two equivalent O(3)La3Hf tetrahedra, corners with five equivalent O(1)La4 tetrahedra, edges with two equivalent O(5)La2Hf2 tetrahedra, and edges with two equivalent O(4)La3Hf tetrahedra. In the fourth O site, O(4) is bonded to one La(1), two equivalent La(2), and one Hf(1) atom to form OLa3Hf tetrahedra that share  a cornercorner with one O(5)La2Hf2 tetrahedra,  a cornercorner with one O(3)La3Hf tetrahedra, corners with two equivalent O(4)La3Hf tetrahedra, corners with five equivalent O(1)La4 tetrahedra,  an edgeedge with one O(1)La4 tetrahedra, edges with two equivalent O(5)La2Hf2 tetrahedra, and edges with two equivalent O(3)La3Hf tetrahedra. In the fifth O site, O(5) is bonded to one La(1), one La(2), and two equivalent Hf(1) atoms to form distorted OLa2Hf2 tetrahedra that share  a cornercorner with one O(3)La3Hf tetrahedra,  a cornercorner with one O(4)La3Hf tetrahedra, corners with two equivalent O(5)La2Hf2 tetrahedra, corners with two equivalent O(1)La4 tetrahedra,  an edgeedge with one O(1)La4 tetrahedra, edges with two equivalent O(3)La3Hf tetrahedra, and edges with two equivalent O(4)La3Hf tetrahedra.