Ba3Y2F12 crystallizes in the tetragonal P4/mbm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a body-centered cubic geometry to eight equivalent F(2) atoms. In the second Ba site, Ba(2) is bonded to two equivalent F(1), two equivalent F(3), and eight equivalent F(2) atoms to form distorted BaF12 cuboctahedra that share corners with two equivalent Ba(2)F12 cuboctahedra, edges with five equivalent Ba(2)F12 cuboctahedra, edges with four equivalent Y(1)F7 pentagonal bipyramids, and faces with two equivalent Y(1)F7 pentagonal bipyramids. Y(1) is bonded to one F(3), two equivalent F(1), and four equivalent F(2) atoms to form distorted YF7 pentagonal bipyramids that share edges with four equivalent Ba(2)F12 cuboctahedra,  an edgeedge with one Y(1)F7 pentagonal bipyramid, and faces with two equivalent Ba(2)F12 cuboctahedra. There are three inequivalent F sites. In the first F site, F(1) is bonded to two equivalent Ba(2) and two equivalent Y(1) atoms to form distorted FBa2Y2 tetrahedra that share corners with sixteen equivalent F(2)Ba3Y tetrahedra, edges with two equivalent F(1)Ba2Y2 tetrahedra, and edges with four equivalent F(2)Ba3Y tetrahedra. In the second F site, F(2) is bonded to one Ba(1), two equivalent Ba(2), and one Y(1) atom to form distorted FBa3Y tetrahedra that share corners with four equivalent F(1)Ba2Y2 tetrahedra, corners with fourteen equivalent F(2)Ba3Y tetrahedra,  an edgeedge with one F(1)Ba2Y2 tetrahedra, and edges with five equivalent F(2)Ba3Y tetrahedra. In the third F site, F(3) is bonded in a distorted T-shaped geometry to two equivalent Ba(2) and one Y(1) atom.
Ba3Y2F12 crystallizes in the tetragonal P4/mbm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a body-centered cubic geometry to eight equivalent F(2) atoms. All Ba(1)-F(2) bond lengths are 2.70 Å. In the second Ba site, Ba(2) is bonded to two equivalent F(1), two equivalent F(3), and eight equivalent F(2) atoms to form distorted BaF12 cuboctahedra that share corners with two equivalent Ba(2)F12 cuboctahedra, edges with five equivalent Ba(2)F12 cuboctahedra, edges with four equivalent Y(1)F7 pentagonal bipyramids, and faces with two equivalent Y(1)F7 pentagonal bipyramids. Both Ba(2)-F(1) bond lengths are 2.93 Å. Both Ba(2)-F(3) bond lengths are 2.92 Å. There are four shorter (2.87 Å) and four longer (2.98 Å) Ba(2)-F(2) bond lengths. Y(1) is bonded to one F(3), two equivalent F(1), and four equivalent F(2) atoms to form distorted YF7 pentagonal bipyramids that share edges with four equivalent Ba(2)F12 cuboctahedra,  an edgeedge with one Y(1)F7 pentagonal bipyramid, and faces with two equivalent Ba(2)F12 cuboctahedra. The Y(1)-F(3) bond length is 2.27 Å. Both Y(1)-F(1) bond lengths are 2.29 Å. All Y(1)-F(2) bond lengths are 2.22 Å. There are three inequivalent F sites. In the first F site, F(1) is bonded to two equivalent Ba(2) and two equivalent Y(1) atoms to form distorted FBa2Y2 tetrahedra that share corners with sixteen equivalent F(2)Ba3Y tetrahedra, edges with two equivalent F(1)Ba2Y2 tetrahedra, and edges with four equivalent F(2)Ba3Y tetrahedra. In the second F site, F(2) is bonded to one Ba(1), two equivalent Ba(2), and one Y(1) atom to form distorted FBa3Y tetrahedra that share corners with four equivalent F(1)Ba2Y2 tetrahedra, corners with fourteen equivalent F(2)Ba3Y tetrahedra,  an edgeedge with one F(1)Ba2Y2 tetrahedra, and edges with five equivalent F(2)Ba3Y tetrahedra. In the third F site, F(3) is bonded in a distorted T-shaped geometry to two equivalent Ba(2) and one Y(1) atom.