Materials Data on CsEr2Cu3Se5 by Materials Project
CsEr2Cu3Se5 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Cs1+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Cs–Se bond distances ranging from 3.49–3.63 Å. Er3+ is bonded to six Se2- atoms to form ErSe6 octahedra that share a cornercorner with one ErSe6 octahedra, corners with four equivalent CuSe4 tetrahedra, edges with four equivalent ErSe6 octahedra, and edges with five CuSe4 tetrahedra. The corner-sharing octahedral tilt angles are 28°. There are a spread of Er–Se bond distances ranging from 2.81–2.92 Å. There are two inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with six CuSe4 tetrahedra and edges with four equivalent ErSe6 octahedra. There are two shorter (2.39 Å) and two longer (2.75 Å) Cu–Se bond lengths. In the second Cu1+ site, Cu1+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with four equivalent ErSe6 octahedra, corners with four CuSe4 tetrahedra, edges with three equivalent ErSe6 octahedra, and an edgeedge with one CuSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 15–60°. There are two shorter (2.50 Å) and two longer (2.53 Å) Cu–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 6-coordinate geometry to two equivalent Cs1+, two equivalent Er3+, and two equivalent Cu1+ atoms. In the second Se2- site, Se2- is bonded in a 7-coordinate geometry to two equivalent Cs1+, two equivalent Er3+, and three Cu1+ atoms. In the third Se2- site, Se2- is bonded to one Cs1+, three equivalent Er3+, and two equivalent Cu1+ atoms to form a mixture of distorted edge and corner-sharing SeCsEr3Cu2 octahedra. The corner-sharing octahedral tilt angles are 54°.