SrAl2O4 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(5), one O(7), and one O(8) atom. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one O(3), one O(5), one O(6), one O(7), one O(8), and two equivalent O(2) atoms. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(2), one O(3), one O(6), and one O(8) atom to form corner-sharing AlO4 tetrahedra. In the second Al site, Al(2) is bonded to one O(2), one O(4), one O(5), and one O(7) atom to form corner-sharing AlO4 tetrahedra. In the third Al site, Al(3) is bonded to one O(1), one O(4), one O(6), and one O(7) atom to form corner-sharing AlO4 tetrahedra. In the fourth Al site, Al(4) is bonded to one O(1), one O(3), one O(5), and one O(8) atom to form corner-sharing AlO4 tetrahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Sr(1), one Al(3), and one Al(4) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Sr(2), one Al(1), and one Al(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(2), one Al(1), and one Al(4) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Sr(1), one Al(2), and one Al(3) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), one Al(2), and one Al(4) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Sr(2), one Al(1), and one Al(3) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Sr(1), one Sr(2), one Al(2), and one Al(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), one Al(1), and one Al(4) atom.
SrAl2O4 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(5), one O(7), and one O(8) atom. The Sr(1)-O(1) bond length is 2.53 Å. The Sr(1)-O(3) bond length is 2.54 Å. The Sr(1)-O(4) bond length is 2.52 Å. The Sr(1)-O(5) bond length is 2.61 Å. The Sr(1)-O(7) bond length is 2.76 Å. The Sr(1)-O(8) bond length is 2.73 Å. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one O(3), one O(5), one O(6), one O(7), one O(8), and two equivalent O(2) atoms. The Sr(2)-O(3) bond length is 3.11 Å. The Sr(2)-O(5) bond length is 2.54 Å. The Sr(2)-O(6) bond length is 2.52 Å. The Sr(2)-O(7) bond length is 2.66 Å. The Sr(2)-O(8) bond length is 2.64 Å. There is one shorter (2.59 Å) and one longer (2.70 Å) Sr(2)-O(2) bond length. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(2), one O(3), one O(6), and one O(8) atom to form corner-sharing AlO4 tetrahedra. The Al(1)-O(2) bond length is 1.76 Å. The Al(1)-O(3) bond length is 1.76 Å. The Al(1)-O(6) bond length is 1.75 Å. The Al(1)-O(8) bond length is 1.75 Å. In the second Al site, Al(2) is bonded to one O(2), one O(4), one O(5), and one O(7) atom to form corner-sharing AlO4 tetrahedra. The Al(2)-O(2) bond length is 1.76 Å. The Al(2)-O(4) bond length is 1.75 Å. The Al(2)-O(5) bond length is 1.76 Å. The Al(2)-O(7) bond length is 1.76 Å. In the third Al site, Al(3) is bonded to one O(1), one O(4), one O(6), and one O(7) atom to form corner-sharing AlO4 tetrahedra. The Al(3)-O(1) bond length is 1.75 Å. The Al(3)-O(4) bond length is 1.77 Å. The Al(3)-O(6) bond length is 1.75 Å. The Al(3)-O(7) bond length is 1.77 Å. In the fourth Al site, Al(4) is bonded to one O(1), one O(3), one O(5), and one O(8) atom to form corner-sharing AlO4 tetrahedra. The Al(4)-O(1) bond length is 1.76 Å. The Al(4)-O(3) bond length is 1.76 Å. The Al(4)-O(5) bond length is 1.76 Å. The Al(4)-O(8) bond length is 1.74 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Sr(1), one Al(3), and one Al(4) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Sr(2), one Al(1), and one Al(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(2), one Al(1), and one Al(4) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Sr(1), one Al(2), and one Al(3) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), one Al(2), and one Al(4) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Sr(2), one Al(1), and one Al(3) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Sr(1), one Sr(2), one Al(2), and one Al(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), one Al(1), and one Al(4) atom.