DOE OSTI2020
Tm2O3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Tm3+ sites. In the first Tm3+ site, Tm3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Tm–O bond distances ranging from 2.20–2.53 Å. In the second Tm3+ site, Tm3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Tm–O bond distances ranging from 2.21–2.70 Å. In the third Tm3+ site, Tm3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing TmO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Tm–O bond distances ranging from 2.17–2.43 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to five Tm3+ atoms to form distorted OTm5 square pyramids that share corners with seven OTm4 tetrahedra, corners with two equivalent OTm4 trigonal pyramids, edges with two equivalent OTm6 octahedra, edges with two equivalent OTm5 square pyramids, edges with three OTm4 tetrahedra, and edges with three equivalent OTm4 trigonal pyramids. In the second O2- site, O2- is bonded to four Tm3+ atoms to form distorted OTm4 trigonal pyramids that share a cornercorner with one OTm6 octahedra, corners with two equivalent OTm5 square pyramids, corners with nine OTm4 tetrahedra, corners with two equivalent OTm4 trigonal pyramids, edges with three equivalent OTm5 square pyramids, and edges with two equivalent OTm4 trigonal pyramids. The corner-sharing octahedral tilt angles are 38°. In the third O2- site, O2- is bonded to four Tm3+ atoms to form distorted OTm4 tetrahedra that share corners with two equivalent OTm6 octahedra, corners with two equivalent OTm5 square pyramids, corners with four OTm4 tetrahedra, corners with six equivalent OTm4 trigonal pyramids, an edgeedge with one OTm6 octahedra, edges with two equivalent OTm5 square pyramids, and an edgeedge with one OTm4 tetrahedra. The corner-sharing octahedral tilt angles are 13°. In the fourth O2- site, O2- is bonded to four Tm3+ atoms to form OTm4 tetrahedra that share a cornercorner with one OTm6 octahedra, corners with five equivalent OTm5 square pyramids, corners with four OTm4 tetrahedra, corners with three equivalent OTm4 trigonal pyramids, edges with two equivalent OTm6 octahedra, an edgeedge with one OTm5 square pyramid, and edges with two equivalent OTm4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. In the fifth O2- site, O2- is bonded to six Tm3+ atoms to form OTm6 octahedra that share corners with six OTm4 tetrahedra, corners with two equivalent OTm4 trigonal pyramids, edges with two equivalent OTm6 octahedra, edges with four equivalent OTm5 square pyramids, and edges with six OTm4 tetrahedra.