Materials Data on ErCuSe2 by Materials Project
ErCuSe2 is Spinel-like structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. Er3+ is bonded to six Se2- atoms to form ErSe6 octahedra that share corners with six equivalent CuSe4 tetrahedra, edges with six equivalent ErSe6 octahedra, and edges with three equivalent CuSe4 tetrahedra. There are three shorter (2.80 Å) and three longer (2.93 Å) Er–Se bond lengths. Cu1+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with six equivalent ErSe6 octahedra, corners with six equivalent CuSe4 tetrahedra, and edges with three equivalent ErSe6 octahedra. The corner-sharing octahedra tilt angles range from 22–58°. There are three shorter (2.44 Å) and one longer (2.47 Å) Cu–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three equivalent Er3+ and three equivalent Cu1+ atoms to form distorted SeEr3Cu3 octahedra that share corners with six equivalent SeEr3Cu trigonal pyramids, edges with six equivalent SeEr3Cu3 octahedra, and edges with three equivalent SeEr3Cu trigonal pyramids. In the second Se2- site, Se2- is bonded to three equivalent Er3+ and one Cu1+ atom to form distorted SeEr3Cu trigonal pyramids that share corners with six equivalent SeEr3Cu3 octahedra, corners with six equivalent SeEr3Cu trigonal pyramids, and edges with three equivalent SeEr3Cu3 octahedra. The corner-sharing octahedra tilt angles range from 4–77°.