DOE OSTI2020
Tb11CuSe16 crystallizes in the orthorhombic P2_12_12 space group. The structure is three-dimensional. there are six inequivalent Tb sites. In the first Tb site, Tb is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of Tb–Se bond distances ranging from 2.88–3.36 Å. In the second Tb site, Tb is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of Tb–Se bond distances ranging from 2.86–3.25 Å. In the third Tb site, Tb is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of Tb–Se bond distances ranging from 2.87–3.25 Å. In the fourth Tb site, Tb is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of Tb–Se bond distances ranging from 2.89–3.20 Å. In the fifth Tb site, Tb is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of Tb–Se bond distances ranging from 2.85–3.34 Å. In the sixth Tb site, Tb is bonded in a 8-coordinate geometry to eight Se atoms. There are a spread of Tb–Se bond distances ranging from 2.86–3.18 Å. Cu is bonded in a distorted square co-planar geometry to four Se atoms. There are two shorter (2.76 Å) and two longer (2.77 Å) Cu–Se bond lengths. There are eight inequivalent Se sites. In the first Se site, Se is bonded to six Tb atoms to form distorted SeTb6 octahedra that share corners with ten SeTb6 octahedra, corners with five SeTb5 square pyramids, edges with four SeTb6 octahedra, edges with two equivalent SeTb5 square pyramids, and faces with five SeTb6 octahedra. The corner-sharing octahedra tilt angles range from 16–53°. In the second Se site, Se is bonded to six Tb atoms to form distorted SeTb6 octahedra that share corners with thirteen SeTb6 octahedra, corners with two SeTb5 square pyramids, edges with five SeTb6 octahedra, an edgeedge with one SeTb5 square pyramid, faces with three SeTb6 octahedra, and faces with two SeTb5 square pyramids. The corner-sharing octahedra tilt angles range from 18–52°. In the third Se site, Se is bonded to five Tb atoms to form distorted SeTb5 square pyramids that share corners with twelve SeTb6 octahedra, a cornercorner with one SeTb5 square pyramid, edges with five SeTb6 octahedra, edges with three SeTb5 square pyramids, and faces with two SeTb6 octahedra. The corner-sharing octahedra tilt angles range from 18–85°. In the fourth Se site, Se is bonded to six Tb atoms to form distorted SeTb6 octahedra that share corners with nine SeTb6 octahedra, corners with six SeTb5 square pyramids, edges with four SeTb6 octahedra, edges with two equivalent SeTb5 square pyramids, and faces with five SeTb6 octahedra. The corner-sharing octahedra tilt angles range from 19–49°. In the fifth Se site, Se is bonded to five Tb and one Cu atom to form distorted SeTb5Cu octahedra that share corners with eleven SeTb6 octahedra, corners with four SeTb5 square pyramids, edges with five SeTb6 octahedra, edges with two SeTb5 square pyramids, and faces with three SeTb6 octahedra. The corner-sharing octahedra tilt angles range from 15–52°. In the sixth Se site, Se is bonded to five Tb and one Cu atom to form distorted SeTb5Cu octahedra that share corners with twelve SeTb6 octahedra, corners with three SeTb5 square pyramids, edges with five SeTb6 octahedra, edges with two SeTb5 square pyramids, and faces with three SeTb6 octahedra. The corner-sharing octahedra tilt angles range from 15–49°. In the seventh Se site, Se is bonded to six Tb atoms to form distorted SeTb6 octahedra that share corners with ten SeTb6 octahedra, corners with five SeTb5 square pyramids, edges with five SeTb6 octahedra, an edgeedge with one SeTb5 square pyramid, faces with three SeTb6 octahedra, and faces with two SeTb5 square pyramids. The corner-sharing octahedra tilt angles range from 23–50°. In the eighth Se site, Se is bonded to five Tb atoms to form distorted SeTb5 square pyramids that share corners with thirteen SeTb6 octahedra, edges with five SeTb6 octahedra, edges with three SeTb5 square pyramids, and faces with two SeTb6 octahedra. The corner-sharing octahedra tilt angles range from 19–85°.