Y4Zr3O12 crystallizes in the triclinic P-1 space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(6), two equivalent O(3), and two equivalent O(5) atoms. In the second Y site, Y(2) is bonded to one O(2), one O(3), one O(4), two equivalent O(1), and two equivalent O(6) atoms to form distorted YO7 pentagonal bipyramids that share  a cornercorner with one Zr(1)O6 octahedra,  an edgeedge with one Zr(1)O6 octahedra, and edges with two equivalent Y(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 50°. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form ZrO6 octahedra that share corners with two equivalent Y(2)O7 pentagonal bipyramids and edges with two equivalent Y(2)O7 pentagonal bipyramids. In the second Zr site, Zr(2) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(5), and two equivalent O(2) atoms. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Y(1), two equivalent Y(2), and one Zr(2) atom to form distorted OY3Zr tetrahedra that share corners with three equivalent O(2)Y2Zr2 tetrahedra, corners with three equivalent O(5)Y2Zr2 tetrahedra, corners with three equivalent O(3)Y3Zr tetrahedra, corners with three equivalent O(6)Y3Zr tetrahedra,  an edgeedge with one O(2)Y2Zr2 tetrahedra,  an edgeedge with one O(1)Y3Zr tetrahedra,  an edgeedge with one O(3)Y3Zr tetrahedra, and  an edgeedge with one O(6)Y3Zr tetrahedra. In the second O site, O(2) is bonded to one Y(1), one Y(2), and two equivalent Zr(2) atoms to form OY2Zr2 tetrahedra that share corners with two equivalent O(5)Y2Zr2 tetrahedra, corners with three equivalent O(1)Y3Zr tetrahedra, corners with three equivalent O(3)Y3Zr tetrahedra, corners with three equivalent O(6)Y3Zr tetrahedra,  an edgeedge with one O(2)Y2Zr2 tetrahedra,  an edgeedge with one O(5)Y2Zr2 tetrahedra,  an edgeedge with one O(1)Y3Zr tetrahedra, and  an edgeedge with one O(3)Y3Zr tetrahedra. In the third O site, O(3) is bonded to one Y(2), two equivalent Y(1), and one Zr(2) atom to form OY3Zr tetrahedra that share corners with two equivalent O(6)Y3Zr tetrahedra, corners with three equivalent O(2)Y2Zr2 tetrahedra, corners with three equivalent O(5)Y2Zr2 tetrahedra, corners with three equivalent O(1)Y3Zr tetrahedra,  an edgeedge with one O(2)Y2Zr2 tetrahedra,  an edgeedge with one O(5)Y2Zr2 tetrahedra,  an edgeedge with one O(1)Y3Zr tetrahedra,  an edgeedge with one O(3)Y3Zr tetrahedra, and  an edgeedge with one O(6)Y3Zr tetrahedra. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Y(2), one Zr(1), and one Zr(2) atom. In the fifth O site, O(5) is bonded to two equivalent Y(1), one Zr(1), and one Zr(2) atom to form distorted OY2Zr2 tetrahedra that share  a cornercorner with one O(5)Y2Zr2 tetrahedra, corners with two equivalent O(2)Y2Zr2 tetrahedra, corners with two equivalent O(6)Y3Zr tetrahedra, corners with three equivalent O(1)Y3Zr tetrahedra, corners with three equivalent O(3)Y3Zr tetrahedra,  an edgeedge with one O(2)Y2Zr2 tetrahedra,  an edgeedge with one O(5)Y2Zr2 tetrahedra,  an edgeedge with one O(3)Y3Zr tetrahedra, and  an edgeedge with one O(6)Y3Zr tetrahedra. In the sixth O site, O(6) is bonded to one Y(1), two equivalent Y(2), and one Zr(1) atom to form distorted OY3Zr tetrahedra that share  a cornercorner with one O(6)Y3Zr tetrahedra, corners with two equivalent O(5)Y2Zr2 tetrahedra, corners with two equivalent O(3)Y3Zr tetrahedra, corners with three equivalent O(2)Y2Zr2 tetrahedra, corners with three equivalent O(1)Y3Zr tetrahedra,  an edgeedge with one O(5)Y2Zr2 tetrahedra,  an edgeedge with one O(1)Y3Zr tetrahedra,  an edgeedge with one O(3)Y3Zr tetrahedra, and  an edgeedge with one O(6)Y3Zr tetrahedra.
Y4Zr3O12 crystallizes in the triclinic P-1 space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(6), two equivalent O(3), and two equivalent O(5) atoms. The Y(1)-O(1) bond length is 2.39 Å. The Y(1)-O(2) bond length is 2.21 Å. The Y(1)-O(6) bond length is 2.28 Å. There is one shorter (2.26 Å) and one longer (2.29 Å) Y(1)-O(3) bond length. There is one shorter (2.35 Å) and one longer (2.54 Å) Y(1)-O(5) bond length. In the second Y site, Y(2) is bonded to one O(2), one O(3), one O(4), two equivalent O(1), and two equivalent O(6) atoms to form distorted YO7 pentagonal bipyramids that share  a cornercorner with one Zr(1)O6 octahedra,  an edgeedge with one Zr(1)O6 octahedra, and edges with two equivalent Y(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 50°. The Y(2)-O(2) bond length is 2.41 Å. The Y(2)-O(3) bond length is 2.22 Å. The Y(2)-O(4) bond length is 2.31 Å. There is one shorter (2.29 Å) and one longer (2.37 Å) Y(2)-O(1) bond length. There is one shorter (2.26 Å) and one longer (2.44 Å) Y(2)-O(6) bond length. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form ZrO6 octahedra that share corners with two equivalent Y(2)O7 pentagonal bipyramids and edges with two equivalent Y(2)O7 pentagonal bipyramids. Both Zr(1)-O(4) bond lengths are 2.10 Å. Both Zr(1)-O(5) bond lengths are 2.17 Å. Both Zr(1)-O(6) bond lengths are 2.07 Å. In the second Zr site, Zr(2) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(5), and two equivalent O(2) atoms. The Zr(2)-O(1) bond length is 2.06 Å. The Zr(2)-O(3) bond length is 2.16 Å. The Zr(2)-O(4) bond length is 2.10 Å. The Zr(2)-O(5) bond length is 2.13 Å. There is one shorter (2.09 Å) and one longer (2.21 Å) Zr(2)-O(2) bond length. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Y(1), two equivalent Y(2), and one Zr(2) atom to form distorted OY3Zr tetrahedra that share corners with three equivalent O(2)Y2Zr2 tetrahedra, corners with three equivalent O(5)Y2Zr2 tetrahedra, corners with three equivalent O(3)Y3Zr tetrahedra, corners with three equivalent O(6)Y3Zr tetrahedra,  an edgeedge with one O(2)Y2Zr2 tetrahedra,  an edgeedge with one O(1)Y3Zr tetrahedra,  an edgeedge with one O(3)Y3Zr tetrahedra, and  an edgeedge with one O(6)Y3Zr tetrahedra. In the second O site, O(2) is bonded to one Y(1), one Y(2), and two equivalent Zr(2) atoms to form OY2Zr2 tetrahedra that share corners with two equivalent O(5)Y2Zr2 tetrahedra, corners with three equivalent O(1)Y3Zr tetrahedra, corners with three equivalent O(3)Y3Zr tetrahedra, corners with three equivalent O(6)Y3Zr tetrahedra,  an edgeedge with one O(2)Y2Zr2 tetrahedra,  an edgeedge with one O(5)Y2Zr2 tetrahedra,  an edgeedge with one O(1)Y3Zr tetrahedra, and  an edgeedge with one O(3)Y3Zr tetrahedra. In the third O site, O(3) is bonded to one Y(2), two equivalent Y(1), and one Zr(2) atom to form OY3Zr tetrahedra that share corners with two equivalent O(6)Y3Zr tetrahedra, corners with three equivalent O(2)Y2Zr2 tetrahedra, corners with three equivalent O(5)Y2Zr2 tetrahedra, corners with three equivalent O(1)Y3Zr tetrahedra,  an edgeedge with one O(2)Y2Zr2 tetrahedra,  an edgeedge with one O(5)Y2Zr2 tetrahedra,  an edgeedge with one O(1)Y3Zr tetrahedra,  an edgeedge with one O(3)Y3Zr tetrahedra, and  an edgeedge with one O(6)Y3Zr tetrahedra. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Y(2), one Zr(1), and one Zr(2) atom. In the fifth O site, O(5) is bonded to two equivalent Y(1), one Zr(1), and one Zr(2) atom to form distorted OY2Zr2 tetrahedra that share  a cornercorner with one O(5)Y2Zr2 tetrahedra, corners with two equivalent O(2)Y2Zr2 tetrahedra, corners with two equivalent O(6)Y3Zr tetrahedra, corners with three equivalent O(1)Y3Zr tetrahedra, corners with three equivalent O(3)Y3Zr tetrahedra,  an edgeedge with one O(2)Y2Zr2 tetrahedra,  an edgeedge with one O(5)Y2Zr2 tetrahedra,  an edgeedge with one O(3)Y3Zr tetrahedra, and  an edgeedge with one O(6)Y3Zr tetrahedra. In the sixth O site, O(6) is bonded to one Y(1), two equivalent Y(2), and one Zr(1) atom to form distorted OY3Zr tetrahedra that share  a cornercorner with one O(6)Y3Zr tetrahedra, corners with two equivalent O(5)Y2Zr2 tetrahedra, corners with two equivalent O(3)Y3Zr tetrahedra, corners with three equivalent O(2)Y2Zr2 tetrahedra, corners with three equivalent O(1)Y3Zr tetrahedra,  an edgeedge with one O(5)Y2Zr2 tetrahedra,  an edgeedge with one O(1)Y3Zr tetrahedra,  an edgeedge with one O(3)Y3Zr tetrahedra, and  an edgeedge with one O(6)Y3Zr tetrahedra.