Ba2YSn3O7 crystallizes in the orthorhombic Pmmm space group. Ba(1) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and four equivalent O(4) atoms. Y(1) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to one O(4), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing SnO5 square pyramids. In the second Sn site, Sn(2) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(4) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ba(1) and two equivalent Sn(2) atoms to form OBa4Sn2 octahedra that share corners with two equivalent O(1)Ba4Sn2 octahedra, corners with four equivalent O(3)Ba2Y2Sn2 octahedra, corners with eight equivalent O(4)Ba4Sn2 octahedra, edges with two equivalent O(3)Ba2Y2Sn2 octahedra, edges with two equivalent O(1)Ba4Sn2 octahedra, and faces with four equivalent O(4)Ba4Sn2 octahedra. The corner-sharing octahedral tilt angles range from 0-57°. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Y(1), and two equivalent Sn(1) atoms. In the third O site, O(3) is bonded to two equivalent Ba(1), two equivalent Y(1), and two equivalent Sn(1) atoms to form distorted OBa2Y2Sn2 octahedra that share corners with two equivalent O(1)Ba4Sn2 octahedra, corners with four equivalent O(3)Ba2Y2Sn2 octahedra, corners with four equivalent O(4)Ba4Sn2 octahedra,  an edgeedge with one O(1)Ba4Sn2 octahedra, edges with three equivalent O(3)Ba2Y2Sn2 octahedra, and faces with two equivalent O(4)Ba4Sn2 octahedra. The corner-sharing octahedral tilt angles range from 0-68°. In the fourth O site, O(4) is bonded to four equivalent Ba(1), one Sn(1), and one Sn(2) atom to form distorted OBa4Sn2 octahedra that share corners with four equivalent O(3)Ba2Y2Sn2 octahedra, corners with four equivalent O(1)Ba4Sn2 octahedra, corners with five equivalent O(4)Ba4Sn2 octahedra, edges with four equivalent O(4)Ba4Sn2 octahedra, faces with two equivalent O(3)Ba2Y2Sn2 octahedra, and faces with two equivalent O(1)Ba4Sn2 octahedra. The corner-sharing octahedral tilt angles range from 0-68°.
Ba2YSn3O7 crystallizes in the orthorhombic Pmmm space group. Ba(1) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and four equivalent O(4) atoms. Both Ba(1)-O(1) bond lengths are 2.95 Å. Both Ba(1)-O(2) bond lengths are 3.30 Å. Both Ba(1)-O(3) bond lengths are 3.22 Å. All Ba(1)-O(4) bond lengths are 3.04 Å. Y(1) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. All Y(1)-O(2) bond lengths are 2.63 Å. All Y(1)-O(3) bond lengths are 2.56 Å. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to one O(4), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing SnO5 square pyramids. The Sn(1)-O(4) bond length is 2.08 Å. Both Sn(1)-O(2) bond lengths are 2.10 Å. Both Sn(1)-O(3) bond lengths are 2.19 Å. In the second Sn site, Sn(2) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(4) atoms. Both Sn(2)-O(1) bond lengths are 2.19 Å. Both Sn(2)-O(4) bond lengths are 2.33 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ba(1) and two equivalent Sn(2) atoms to form OBa4Sn2 octahedra that share corners with two equivalent O(1)Ba4Sn2 octahedra, corners with four equivalent O(3)Ba2Y2Sn2 octahedra, corners with eight equivalent O(4)Ba4Sn2 octahedra, edges with two equivalent O(3)Ba2Y2Sn2 octahedra, edges with two equivalent O(1)Ba4Sn2 octahedra, and faces with four equivalent O(4)Ba4Sn2 octahedra. The corner-sharing octahedral tilt angles range from 0-57°. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Y(1), and two equivalent Sn(1) atoms. In the third O site, O(3) is bonded to two equivalent Ba(1), two equivalent Y(1), and two equivalent Sn(1) atoms to form distorted OBa2Y2Sn2 octahedra that share corners with two equivalent O(1)Ba4Sn2 octahedra, corners with four equivalent O(3)Ba2Y2Sn2 octahedra, corners with four equivalent O(4)Ba4Sn2 octahedra,  an edgeedge with one O(1)Ba4Sn2 octahedra, edges with three equivalent O(3)Ba2Y2Sn2 octahedra, and faces with two equivalent O(4)Ba4Sn2 octahedra. The corner-sharing octahedral tilt angles range from 0-68°. In the fourth O site, O(4) is bonded to four equivalent Ba(1), one Sn(1), and one Sn(2) atom to form distorted OBa4Sn2 octahedra that share corners with four equivalent O(3)Ba2Y2Sn2 octahedra, corners with four equivalent O(1)Ba4Sn2 octahedra, corners with five equivalent O(4)Ba4Sn2 octahedra, edges with four equivalent O(4)Ba4Sn2 octahedra, faces with two equivalent O(3)Ba2Y2Sn2 octahedra, and faces with two equivalent O(1)Ba4Sn2 octahedra. The corner-sharing octahedral tilt angles range from 0-68°.