BaYCu4O7 crystallizes in the hexagonal P6_3mc space group. Ba(1) is bonded in a 9-coordinate geometry to three equivalent O(3) and six equivalent O(1) atoms. Y(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form YO6 octahedra that share corners with three equivalent Cu(2)O4 tetrahedra and corners with nine equivalent Cu(1)O4 tetrahedra. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form CuO4 tetrahedra that share corners with three equivalent Y(1)O6 octahedra, corners with two equivalent Cu(2)O4 tetrahedra, and corners with four equivalent Cu(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-56°. In the second Cu site, Cu(2) is bonded to one O(2) and three equivalent O(1) atoms to form CuO4 tetrahedra that share corners with three equivalent Y(1)O6 octahedra and corners with six equivalent Cu(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Ba(1), one Y(1), one Cu(1), and one Cu(2) atom. In the second O site, O(2) is bonded in a tetrahedral geometry to one Cu(2) and three equivalent Cu(1) atoms. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ba(1), one Y(1), and two equivalent Cu(1) atoms.
BaYCu4O7 crystallizes in the hexagonal P6_3mc space group. Ba(1) is bonded in a 9-coordinate geometry to three equivalent O(3) and six equivalent O(1) atoms. All Ba(1)-O(3) bond lengths are 2.86 Å. All Ba(1)-O(1) bond lengths are 3.16 Å. Y(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form YO6 octahedra that share corners with three equivalent Cu(2)O4 tetrahedra and corners with nine equivalent Cu(1)O4 tetrahedra. All Y(1)-O(1) bond lengths are 2.29 Å. All Y(1)-O(3) bond lengths are 2.25 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form CuO4 tetrahedra that share corners with three equivalent Y(1)O6 octahedra, corners with two equivalent Cu(2)O4 tetrahedra, and corners with four equivalent Cu(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-56°. The Cu(1)-O(1) bond length is 1.91 Å. The Cu(1)-O(2) bond length is 1.96 Å. Both Cu(1)-O(3) bond lengths are 1.94 Å. In the second Cu site, Cu(2) is bonded to one O(2) and three equivalent O(1) atoms to form CuO4 tetrahedra that share corners with three equivalent Y(1)O6 octahedra and corners with six equivalent Cu(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. The Cu(2)-O(2) bond length is 1.93 Å. All Cu(2)-O(1) bond lengths are 1.92 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Ba(1), one Y(1), one Cu(1), and one Cu(2) atom. In the second O site, O(2) is bonded in a tetrahedral geometry to one Cu(2) and three equivalent Cu(1) atoms. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ba(1), one Y(1), and two equivalent Cu(1) atoms.