Dy2Se3 is Stibnite structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 8-coordinate geometry to two equivalent Se(2), three equivalent Se(1), and three equivalent Se(3) atoms. In the second Dy site, Dy(2) is bonded to two equivalent Se(1), two equivalent Se(3), and three equivalent Se(2) atoms to form a mixture of distorted corner and edge-sharing DySe7 pentagonal bipyramids. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to two equivalent Dy(2) and three equivalent Dy(1) atoms. In the second Se site, Se(2) is bonded to two equivalent Dy(1) and three equivalent Dy(2) atoms to form a mixture of corner and edge-sharing SeDy5 square pyramids. In the third Se site, Se(3) is bonded to two equivalent Dy(2) and three equivalent Dy(1) atoms to form a mixture of distorted corner and edge-sharing SeDy5 trigonal bipyramids.
Dy2Se3 is Stibnite structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 8-coordinate geometry to two equivalent Se(2), three equivalent Se(1), and three equivalent Se(3) atoms. Both Dy(1)-Se(2) bond lengths are 2.96 Å. There are two shorter (2.94 Å) and one longer (3.50 Å) Dy(1)-Se(1) bond length. There are two shorter (2.95 Å) and one longer (2.97 Å) Dy(1)-Se(3) bond length. In the second Dy site, Dy(2) is bonded to two equivalent Se(1), two equivalent Se(3), and three equivalent Se(2) atoms to form a mixture of distorted corner and edge-sharing DySe7 pentagonal bipyramids. There is one shorter (2.90 Å) and one longer (2.95 Å) Dy(2)-Se(1) bond length. Both Dy(2)-Se(3) bond lengths are 2.89 Å. There are two shorter (2.87 Å) and one longer (2.92 Å) Dy(2)-Se(2) bond length. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to two equivalent Dy(2) and three equivalent Dy(1) atoms. In the second Se site, Se(2) is bonded to two equivalent Dy(1) and three equivalent Dy(2) atoms to form a mixture of corner and edge-sharing SeDy5 square pyramids. In the third Se site, Se(3) is bonded to two equivalent Dy(2) and three equivalent Dy(1) atoms to form a mixture of distorted corner and edge-sharing SeDy5 trigonal bipyramids.