DOE OSTI2020
Tb2O3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Tb3+ sites. In the first Tb3+ site, Tb3+ is bonded to six O2- atoms to form a mixture of distorted corner and edge-sharing TbO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Tb–O bond distances ranging from 2.22–2.50 Å. In the second Tb3+ site, Tb3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Tb–O bond distances ranging from 2.26–2.75 Å. In the third Tb3+ site, Tb3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Tb–O bond distances ranging from 2.26–2.61 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to six Tb3+ atoms to form OTb6 octahedra that share corners with six OTb4 tetrahedra, corners with two equivalent OTb4 trigonal pyramids, edges with two equivalent OTb6 octahedra, edges with four equivalent OTb5 square pyramids, and edges with six OTb4 tetrahedra. In the second O2- site, O2- is bonded to four Tb3+ atoms to form OTb4 tetrahedra that share corners with two equivalent OTb6 octahedra, corners with two equivalent OTb5 square pyramids, corners with four OTb4 tetrahedra, corners with six equivalent OTb4 trigonal pyramids, an edgeedge with one OTb6 octahedra, edges with two equivalent OTb5 square pyramids, and an edgeedge with one OTb4 tetrahedra. The corner-sharing octahedral tilt angles are 13°. In the third O2- site, O2- is bonded to four Tb3+ atoms to form distorted OTb4 trigonal pyramids that share a cornercorner with one OTb6 octahedra, corners with two equivalent OTb5 square pyramids, corners with nine OTb4 tetrahedra, corners with two equivalent OTb4 trigonal pyramids, edges with three equivalent OTb5 square pyramids, and edges with two equivalent OTb4 trigonal pyramids. The corner-sharing octahedral tilt angles are 37°. In the fourth O2- site, O2- is bonded to four Tb3+ atoms to form OTb4 tetrahedra that share a cornercorner with one OTb6 octahedra, corners with five equivalent OTb5 square pyramids, corners with four OTb4 tetrahedra, corners with three equivalent OTb4 trigonal pyramids, edges with two equivalent OTb6 octahedra, an edgeedge with one OTb5 square pyramid, and edges with two equivalent OTb4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. In the fifth O2- site, O2- is bonded to five Tb3+ atoms to form distorted OTb5 square pyramids that share corners with seven OTb4 tetrahedra, corners with two equivalent OTb4 trigonal pyramids, edges with two equivalent OTb6 octahedra, edges with two equivalent OTb5 square pyramids, edges with three OTb4 tetrahedra, and edges with three equivalent OTb4 trigonal pyramids.