Y2Al(BeB)O7 crystallizes in the orthorhombic P2_12_12_1 space group. Be(1) is bonded to one O(3), one O(5), one O(6), and one O(7) atom to form distorted BeO4 trigonal pyramids that share  a cornercorner with one Al(1)O5 trigonal bipyramid and  an edgeedge with one Al(1)O5 trigonal bipyramid. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(5), one O(6), and two equivalent O(2) atoms. In the second Y site, Y(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(7) atom. Al(1) is bonded to one O(2), one O(3), one O(4), one O(5), and one O(7) atom to form AlO5 trigonal bipyramids that share  a cornercorner with one Be(1)O4 trigonal pyramid and  an edgeedge with one Be(1)O4 trigonal pyramid. B(1) is bonded in a trigonal planar geometry to one O(1), one O(6), and one O(7) atom. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Y(1), one Y(2), and one B(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Y(2), two equivalent Y(1), and one Al(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Be(1), one Y(1), one Y(2), and one Al(1) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Y(1), one Y(2), and one Al(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Be(1), one Y(1), and one Al(1) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Be(1), one Y(1), and one B(1) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Be(1), one Y(2), one Al(1), and one B(1) atom.
Y2Al(BeB)O7 crystallizes in the orthorhombic P2_12_12_1 space group. Be(1) is bonded to one O(3), one O(5), one O(6), and one O(7) atom to form distorted BeO4 trigonal pyramids that share  a cornercorner with one Al(1)O5 trigonal bipyramid and  an edgeedge with one Al(1)O5 trigonal bipyramid. The Be(1)-O(3) bond length is 1.59 Å. The Be(1)-O(5) bond length is 1.55 Å. The Be(1)-O(6) bond length is 1.70 Å. The Be(1)-O(7) bond length is 1.78 Å. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(5), one O(6), and two equivalent O(2) atoms. The Y(1)-O(1) bond length is 2.45 Å. The Y(1)-O(3) bond length is 2.43 Å. The Y(1)-O(4) bond length is 2.28 Å. The Y(1)-O(5) bond length is 2.35 Å. The Y(1)-O(6) bond length is 2.37 Å. There is one shorter (2.40 Å) and one longer (2.76 Å) Y(1)-O(2) bond length. In the second Y site, Y(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(7) atom. The Y(2)-O(1) bond length is 2.45 Å. The Y(2)-O(2) bond length is 2.17 Å. The Y(2)-O(3) bond length is 2.43 Å. The Y(2)-O(4) bond length is 2.14 Å. The Y(2)-O(7) bond length is 2.31 Å. Al(1) is bonded to one O(2), one O(3), one O(4), one O(5), and one O(7) atom to form AlO5 trigonal bipyramids that share  a cornercorner with one Be(1)O4 trigonal pyramid and  an edgeedge with one Be(1)O4 trigonal pyramid. The Al(1)-O(2) bond length is 1.82 Å. The Al(1)-O(3) bond length is 1.86 Å. The Al(1)-O(4) bond length is 1.85 Å. The Al(1)-O(5) bond length is 1.87 Å. The Al(1)-O(7) bond length is 1.97 Å. B(1) is bonded in a trigonal planar geometry to one O(1), one O(6), and one O(7) atom. The B(1)-O(1) bond length is 1.35 Å. The B(1)-O(6) bond length is 1.38 Å. The B(1)-O(7) bond length is 1.43 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Y(1), one Y(2), and one B(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Y(2), two equivalent Y(1), and one Al(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Be(1), one Y(1), one Y(2), and one Al(1) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Y(1), one Y(2), and one Al(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Be(1), one Y(1), and one Al(1) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Be(1), one Y(1), and one B(1) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Be(1), one Y(2), one Al(1), and one B(1) atom.