Al3Si3(PbO8)2 crystallizes in the orthorhombic Ccc2 space group. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(3) and two equivalent O(6) atoms to form AlO4 tetrahedra that share corners with four equivalent Si(2)O4 tetrahedra. In the second Al site, Al(2) is bonded to one O(4), one O(5), one O(7), and one O(8) atom to form AlO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. Pb(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(5), and two equivalent O(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent O(5) and two equivalent O(8) atoms to form SiO4 tetrahedra that share corners with four equivalent Al(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(3), one O(4), one O(6), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Al(2)O4 tetrahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one Pb(1) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to two equivalent Pb(1) atoms. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Al(1), one Pb(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Al(2), one Pb(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Al(2), one Pb(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(2) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(1) atom.
Al3Si3(PbO8)2 crystallizes in the orthorhombic Ccc2 space group. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(3) and two equivalent O(6) atoms to form AlO4 tetrahedra that share corners with four equivalent Si(2)O4 tetrahedra. Both Al(1)-O(3) bond lengths are 1.78 Å. Both Al(1)-O(6) bond lengths are 1.74 Å. In the second Al site, Al(2) is bonded to one O(4), one O(5), one O(7), and one O(8) atom to form AlO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. The Al(2)-O(4) bond length is 1.80 Å. The Al(2)-O(5) bond length is 1.77 Å. The Al(2)-O(7) bond length is 1.72 Å. The Al(2)-O(8) bond length is 1.75 Å. Pb(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(5), and two equivalent O(2) atoms. The Pb(1)-O(1) bond length is 2.29 Å. The Pb(1)-O(3) bond length is 2.54 Å. The Pb(1)-O(4) bond length is 2.47 Å. The Pb(1)-O(5) bond length is 2.54 Å. There is one shorter (2.62 Å) and one longer (2.63 Å) Pb(1)-O(2) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent O(5) and two equivalent O(8) atoms to form SiO4 tetrahedra that share corners with four equivalent Al(2)O4 tetrahedra. Both Si(1)-O(5) bond lengths are 1.66 Å. Both Si(1)-O(8) bond lengths are 1.62 Å. In the second Si site, Si(2) is bonded to one O(3), one O(4), one O(6), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Al(2)O4 tetrahedra. The Si(2)-O(3) bond length is 1.65 Å. The Si(2)-O(4) bond length is 1.68 Å. The Si(2)-O(6) bond length is 1.63 Å. The Si(2)-O(7) bond length is 1.60 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one Pb(1) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to two equivalent Pb(1) atoms. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Al(1), one Pb(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Al(2), one Pb(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Al(2), one Pb(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(2) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(1) atom.