DOE OSTI2020
ErCu3Te3 crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. Er3+ is bonded to six Te2- atoms to form ErTe6 octahedra that share corners with four equivalent ErTe6 octahedra, corners with ten CuTe4 tetrahedra, an edgeedge with one ErTe6 octahedra, edges with four CuTe4 tetrahedra, and faces with two CuTe4 tetrahedra. The corner-sharing octahedra tilt angles range from 46–48°. There are a spread of Er–Te bond distances ranging from 3.01–3.10 Å. There are four inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded to four Te2- atoms to form CuTe4 tetrahedra that share corners with three equivalent ErTe6 octahedra, corners with ten CuTe4 tetrahedra, an edgeedge with one ErTe6 octahedra, an edgeedge with one CuTe4 tetrahedra, and a faceface with one ErTe6 octahedra. The corner-sharing octahedra tilt angles range from 54–63°. There are a spread of Cu–Te bond distances ranging from 2.59–2.74 Å. In the second Cu1+ site, Cu1+ is bonded to four Te2- atoms to form CuTe4 tetrahedra that share corners with four equivalent ErTe6 octahedra, corners with ten CuTe4 tetrahedra, edges with two equivalent ErTe6 octahedra, and an edgeedge with one CuTe4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–64°. There are a spread of Cu–Te bond distances ranging from 2.62–2.65 Å. In the third Cu1+ site, Cu1+ is bonded to four Te2- atoms to form CuTe4 tetrahedra that share corners with three equivalent ErTe6 octahedra, corners with ten CuTe4 tetrahedra, an edgeedge with one ErTe6 octahedra, an edgeedge with one CuTe4 tetrahedra, and a faceface with one ErTe6 octahedra. The corner-sharing octahedra tilt angles range from 51–67°. There are a spread of Cu–Te bond distances ranging from 2.58–2.77 Å. In the fourth Cu1+ site, Cu1+ is bonded to four Te2- atoms to form CuTe4 tetrahedra that share corners with four equivalent ErTe6 octahedra, corners with ten CuTe4 tetrahedra, edges with two equivalent ErTe6 octahedra, and an edgeedge with one CuTe4 tetrahedra. The corner-sharing octahedra tilt angles range from 48–61°. There are a spread of Cu–Te bond distances ranging from 2.63–2.70 Å. There are four inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a distorted hexagonal planar geometry to two equivalent Er3+ and four Cu1+ atoms. In the second Te2- site, Te2- is bonded in a distorted hexagonal planar geometry to two equivalent Er3+ and four Cu1+ atoms. In the third Te2- site, Te2- is bonded in a 6-coordinate geometry to two equivalent Er3+ and four Cu1+ atoms. In the fourth Te2- site, Te2- is bonded in a 6-coordinate geometry to two equivalent Er3+ and four Cu1+ atoms.