Y3AlO6 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(4), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted YO7 pentagonal bipyramids that share  a cornercorner with one Y(2)O7 hexagonal pyramid, corners with four equivalent Y(1)O7 pentagonal bipyramids, corners with three equivalent Al(1)O4 tetrahedra, edges with three equivalent Y(2)O7 hexagonal pyramids, edges with two equivalent Y(1)O7 pentagonal bipyramids,  an edgeedge with one Al(1)O4 tetrahedra, and  a faceface with one Y(1)O7 pentagonal bipyramid. In the second Y site, Y(2) is bonded to one O(4), two equivalent O(2), and four equivalent O(1) atoms to form distorted YO7 hexagonal pyramids that share corners with two equivalent Y(1)O7 pentagonal bipyramids,  a cornercorner with one Al(1)O4 tetrahedra, edges with two equivalent Y(2)O7 hexagonal pyramids, edges with six equivalent Y(1)O7 pentagonal bipyramids, and  an edgeedge with one Al(1)O4 tetrahedra. Al(1) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form AlO4 tetrahedra that share  a cornercorner with one Y(2)O7 hexagonal pyramid, corners with six equivalent Y(1)O7 pentagonal bipyramids,  an edgeedge with one Y(2)O7 hexagonal pyramid, and edges with two equivalent Y(1)O7 pentagonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Y(1) and two equivalent Y(2) atoms to form OY4 tetrahedra that share corners with two equivalent O(1)Y4 tetrahedra, corners with six equivalent O(2)Y3Al trigonal pyramids, edges with three equivalent O(1)Y4 tetrahedra, and  an edgeedge with one O(2)Y3Al trigonal pyramid. In the second O site, O(2) is bonded to one Y(2), two equivalent Y(1), and one Al(1) atom to form distorted OY3Al trigonal pyramids that share corners with six equivalent O(1)Y4 tetrahedra, corners with two equivalent O(2)Y3Al trigonal pyramids,  an edgeedge with one O(1)Y4 tetrahedra, and  an edgeedge with one O(2)Y3Al trigonal pyramid. In the third O site, O(3) is bonded in a distorted single-bond geometry to four equivalent Y(1) and one Al(1) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Y(2), two equivalent Y(1), and one Al(1) atom.
Y3AlO6 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(4), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted YO7 pentagonal bipyramids that share  a cornercorner with one Y(2)O7 hexagonal pyramid, corners with four equivalent Y(1)O7 pentagonal bipyramids, corners with three equivalent Al(1)O4 tetrahedra, edges with three equivalent Y(2)O7 hexagonal pyramids, edges with two equivalent Y(1)O7 pentagonal bipyramids,  an edgeedge with one Al(1)O4 tetrahedra, and  a faceface with one Y(1)O7 pentagonal bipyramid. The Y(1)-O(4) bond length is 2.36 Å. There is one shorter (2.18 Å) and one longer (2.23 Å) Y(1)-O(1) bond length. There is one shorter (2.26 Å) and one longer (2.38 Å) Y(1)-O(2) bond length. There is one shorter (2.53 Å) and one longer (2.57 Å) Y(1)-O(3) bond length. In the second Y site, Y(2) is bonded to one O(4), two equivalent O(2), and four equivalent O(1) atoms to form distorted YO7 hexagonal pyramids that share corners with two equivalent Y(1)O7 pentagonal bipyramids,  a cornercorner with one Al(1)O4 tetrahedra, edges with two equivalent Y(2)O7 hexagonal pyramids, edges with six equivalent Y(1)O7 pentagonal bipyramids, and  an edgeedge with one Al(1)O4 tetrahedra. The Y(2)-O(4) bond length is 2.44 Å. Both Y(2)-O(2) bond lengths are 2.43 Å. There are two shorter (2.25 Å) and two longer (2.28 Å) Y(2)-O(1) bond lengths. Al(1) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form AlO4 tetrahedra that share  a cornercorner with one Y(2)O7 hexagonal pyramid, corners with six equivalent Y(1)O7 pentagonal bipyramids,  an edgeedge with one Y(2)O7 hexagonal pyramid, and edges with two equivalent Y(1)O7 pentagonal bipyramids. The Al(1)-O(3) bond length is 1.78 Å. The Al(1)-O(4) bond length is 1.77 Å. Both Al(1)-O(2) bond lengths are 1.77 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Y(1) and two equivalent Y(2) atoms to form OY4 tetrahedra that share corners with two equivalent O(1)Y4 tetrahedra, corners with six equivalent O(2)Y3Al trigonal pyramids, edges with three equivalent O(1)Y4 tetrahedra, and  an edgeedge with one O(2)Y3Al trigonal pyramid. In the second O site, O(2) is bonded to one Y(2), two equivalent Y(1), and one Al(1) atom to form distorted OY3Al trigonal pyramids that share corners with six equivalent O(1)Y4 tetrahedra, corners with two equivalent O(2)Y3Al trigonal pyramids,  an edgeedge with one O(1)Y4 tetrahedra, and  an edgeedge with one O(2)Y3Al trigonal pyramid. In the third O site, O(3) is bonded in a distorted single-bond geometry to four equivalent Y(1) and one Al(1) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Y(2), two equivalent Y(1), and one Al(1) atom.