Ba3YF9 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one F(3), one F(6), two equivalent F(2), and four equivalent F(5) atoms. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one F(4), two equivalent F(5), two equivalent F(6), and four equivalent F(1) atoms. In the third Ba site, Ba(3) is bonded in a 7-coordinate geometry to one F(4), two equivalent F(1), two equivalent F(2), and two equivalent F(5) atoms. Y(1) is bonded in an octahedral geometry to one F(3), one F(6), two equivalent F(1), and two equivalent F(2) atoms. There are six inequivalent F sites. In the first F site, F(1) is bonded to one Ba(3), two equivalent Ba(2), and one Y(1) atom to form distorted FBa3Y tetrahedra that share corners with two equivalent F(1)Ba3Y tetrahedra, corners with four equivalent F(5)Ba4 tetrahedra,  an edgeedge with one F(5)Ba4 tetrahedra, and edges with three equivalent F(1)Ba3Y tetrahedra. In the second F site, F(2) is bonded in a 3-coordinate geometry to one Ba(1), one Ba(3), and one Y(1) atom. In the third F site, F(3) is bonded in a distorted single-bond geometry to one Ba(1) and one Y(1) atom. In the fourth F site, F(4) is bonded in a bent 150 degrees geometry to one Ba(2) and one Ba(3) atom. In the fifth F site, F(5) is bonded to one Ba(2), one Ba(3), and two equivalent Ba(1) atoms to form FBa4 tetrahedra that share corners with two equivalent F(5)Ba4 tetrahedra, corners with four equivalent F(1)Ba3Y tetrahedra,  an edgeedge with one F(1)Ba3Y tetrahedra, and edges with three equivalent F(5)Ba4 tetrahedra. In the sixth F site, F(6) is bonded in a 2-coordinate geometry to one Ba(1), two equivalent Ba(2), and one Y(1) atom.
Ba3YF9 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one F(3), one F(6), two equivalent F(2), and four equivalent F(5) atoms. The Ba(1)-F(3) bond length is 2.92 Å. The Ba(1)-F(6) bond length is 2.65 Å. Both Ba(1)-F(2) bond lengths are 2.82 Å. There are two shorter (2.69 Å) and two longer (2.71 Å) Ba(1)-F(5) bond lengths. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one F(4), two equivalent F(5), two equivalent F(6), and four equivalent F(1) atoms. The Ba(2)-F(4) bond length is 2.50 Å. Both Ba(2)-F(5) bond lengths are 2.66 Å. Both Ba(2)-F(6) bond lengths are 3.20 Å. There are two shorter (2.79 Å) and two longer (2.86 Å) Ba(2)-F(1) bond lengths. In the third Ba site, Ba(3) is bonded in a 7-coordinate geometry to one F(4), two equivalent F(1), two equivalent F(2), and two equivalent F(5) atoms. The Ba(3)-F(4) bond length is 2.63 Å. Both Ba(3)-F(1) bond lengths are 2.79 Å. Both Ba(3)-F(2) bond lengths are 2.60 Å. Both Ba(3)-F(5) bond lengths are 2.87 Å. Y(1) is bonded in an octahedral geometry to one F(3), one F(6), two equivalent F(1), and two equivalent F(2) atoms. The Y(1)-F(3) bond length is 2.20 Å. The Y(1)-F(6) bond length is 2.17 Å. Both Y(1)-F(1) bond lengths are 2.24 Å. Both Y(1)-F(2) bond lengths are 2.16 Å. There are six inequivalent F sites. In the first F site, F(1) is bonded to one Ba(3), two equivalent Ba(2), and one Y(1) atom to form distorted FBa3Y tetrahedra that share corners with two equivalent F(1)Ba3Y tetrahedra, corners with four equivalent F(5)Ba4 tetrahedra,  an edgeedge with one F(5)Ba4 tetrahedra, and edges with three equivalent F(1)Ba3Y tetrahedra. In the second F site, F(2) is bonded in a 3-coordinate geometry to one Ba(1), one Ba(3), and one Y(1) atom. In the third F site, F(3) is bonded in a distorted single-bond geometry to one Ba(1) and one Y(1) atom. In the fourth F site, F(4) is bonded in a bent 150 degrees geometry to one Ba(2) and one Ba(3) atom. In the fifth F site, F(5) is bonded to one Ba(2), one Ba(3), and two equivalent Ba(1) atoms to form FBa4 tetrahedra that share corners with two equivalent F(5)Ba4 tetrahedra, corners with four equivalent F(1)Ba3Y tetrahedra,  an edgeedge with one F(1)Ba3Y tetrahedra, and edges with three equivalent F(5)Ba4 tetrahedra. In the sixth F site, F(6) is bonded in a 2-coordinate geometry to one Ba(1), two equivalent Ba(2), and one Y(1) atom.