LiAlSi2O7 crystallizes in the triclinic P1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(13), one O(2), and one O(6) atom to form LiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Al(1)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. In the second Li site, Li(2) is bonded to one O(12), one O(14), one O(7), and one O(8) atom to form LiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Al(2)O4 tetrahedra, and corners with two equivalent Si(4)O4 tetrahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(12), one O(5), and one O(6) atom to form AlO4 tetrahedra that share  a cornercorner with one Li(2)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Li(1)O4 tetrahedra, and corners with two equivalent Si(4)O4 tetrahedra. In the second Al site, Al(2) is bonded to one O(2), one O(7), one O(8), and one O(9) atom to form AlO4 tetrahedra that share  a cornercorner with one Li(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Li(2)O4 tetrahedra,  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Li(1)O4 tetrahedra, and corners with two equivalent Al(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(10), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(10), one O(11), one O(4), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(11), one O(12), one O(6), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Li(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Li(1), one Al(1), and one Si(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Li(1), one Al(2), and one Si(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Li(1), one Al(1), and one Si(4) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Li(2), one Al(2), and one Si(4) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Li(2), one Al(2), and one Si(1) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(3) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Si(3) and one Si(4) atom. In the twelfth O site, O(12) is bonded in a trigonal planar geometry to one Li(2), one Al(1), and one Si(4) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one Li(1) atom. In the fourteenth O site, O(14) is bonded in a distorted single-bond geometry to one Li(2) atom.
LiAlSi2O7 crystallizes in the triclinic P1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(13), one O(2), and one O(6) atom to form LiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Al(1)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The Li(1)-O(1) bond length is 1.98 Å. The Li(1)-O(13) bond length is 2.21 Å. The Li(1)-O(2) bond length is 2.02 Å. The Li(1)-O(6) bond length is 1.96 Å. In the second Li site, Li(2) is bonded to one O(12), one O(14), one O(7), and one O(8) atom to form LiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Al(2)O4 tetrahedra, and corners with two equivalent Si(4)O4 tetrahedra. The Li(2)-O(12) bond length is 1.96 Å. The Li(2)-O(14) bond length is 2.20 Å. The Li(2)-O(7) bond length is 1.96 Å. The Li(2)-O(8) bond length is 1.97 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(12), one O(5), and one O(6) atom to form AlO4 tetrahedra that share  a cornercorner with one Li(2)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Li(1)O4 tetrahedra, and corners with two equivalent Si(4)O4 tetrahedra. The Al(1)-O(1) bond length is 1.77 Å. The Al(1)-O(12) bond length is 1.76 Å. The Al(1)-O(5) bond length is 1.73 Å. The Al(1)-O(6) bond length is 1.77 Å. In the second Al site, Al(2) is bonded to one O(2), one O(7), one O(8), and one O(9) atom to form AlO4 tetrahedra that share  a cornercorner with one Li(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The Al(2)-O(2) bond length is 1.78 Å. The Al(2)-O(7) bond length is 1.77 Å. The Al(2)-O(8) bond length is 1.77 Å. The Al(2)-O(9) bond length is 1.75 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Li(2)O4 tetrahedra,  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Li(1)O4 tetrahedra, and corners with two equivalent Al(2)O4 tetrahedra. The Si(1)-O(1) bond length is 1.64 Å. The Si(1)-O(2) bond length is 1.64 Å. The Si(1)-O(3) bond length is 1.63 Å. The Si(1)-O(8) bond length is 1.64 Å. In the second Si site, Si(2) is bonded to one O(10), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The Si(2)-O(10) bond length is 1.64 Å. The Si(2)-O(3) bond length is 1.64 Å. The Si(2)-O(4) bond length is 1.63 Å. The Si(2)-O(5) bond length is 1.61 Å. In the third Si site, Si(3) is bonded to one O(10), one O(11), one O(4), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The Si(3)-O(10) bond length is 1.63 Å. The Si(3)-O(11) bond length is 1.62 Å. The Si(3)-O(4) bond length is 1.64 Å. The Si(3)-O(9) bond length is 1.62 Å. In the fourth Si site, Si(4) is bonded to one O(11), one O(12), one O(6), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Li(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. The Si(4)-O(11) bond length is 1.63 Å. The Si(4)-O(12) bond length is 1.63 Å. The Si(4)-O(6) bond length is 1.64 Å. The Si(4)-O(7) bond length is 1.64 Å. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Li(1), one Al(1), and one Si(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Li(1), one Al(2), and one Si(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Li(1), one Al(1), and one Si(4) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Li(2), one Al(2), and one Si(4) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Li(2), one Al(2), and one Si(1) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(3) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Si(3) and one Si(4) atom. In the twelfth O site, O(12) is bonded in a trigonal planar geometry to one Li(2), one Al(1), and one Si(4) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one Li(1) atom. In the fourteenth O site, O(14) is bonded in a distorted single-bond geometry to one Li(2) atom.