DOE OSTI2020
Sc2O3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Sc3+ sites. In the first Sc3+ site, Sc3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing ScO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Sc–O bond distances ranging from 2.05–2.27 Å. In the second Sc3+ site, Sc3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Sc–O bond distances ranging from 2.08–2.38 Å. In the third Sc3+ site, Sc3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Sc–O bond distances ranging from 2.10–2.60 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to four Sc3+ atoms to form OSc4 tetrahedra that share a cornercorner with one OSc6 octahedra, corners with four OSc4 tetrahedra, corners with five equivalent OSc5 trigonal bipyramids, corners with three equivalent OSc4 trigonal pyramids, edges with two equivalent OSc6 octahedra, edges with two equivalent OSc4 tetrahedra, and an edgeedge with one OSc5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 47°. In the second O2- site, O2- is bonded to four Sc3+ atoms to form distorted OSc4 trigonal pyramids that share a cornercorner with one OSc6 octahedra, corners with nine OSc4 tetrahedra, corners with two equivalent OSc5 trigonal bipyramids, corners with two equivalent OSc4 trigonal pyramids, edges with three equivalent OSc5 trigonal bipyramids, and edges with two equivalent OSc4 trigonal pyramids. The corner-sharing octahedral tilt angles are 39°. In the third O2- site, O2- is bonded to five Sc3+ atoms to form distorted OSc5 trigonal bipyramids that share corners with seven OSc4 tetrahedra, corners with two equivalent OSc4 trigonal pyramids, edges with two equivalent OSc6 octahedra, edges with three OSc4 tetrahedra, edges with two equivalent OSc5 trigonal bipyramids, and edges with three equivalent OSc4 trigonal pyramids. In the fourth O2- site, O2- is bonded to six Sc3+ atoms to form OSc6 octahedra that share corners with six OSc4 tetrahedra, corners with two equivalent OSc4 trigonal pyramids, edges with two equivalent OSc6 octahedra, edges with six OSc4 tetrahedra, and edges with four equivalent OSc5 trigonal bipyramids. In the fifth O2- site, O2- is bonded to four Sc3+ atoms to form distorted OSc4 tetrahedra that share corners with two equivalent OSc6 octahedra, corners with four OSc4 tetrahedra, corners with two equivalent OSc5 trigonal bipyramids, corners with six equivalent OSc4 trigonal pyramids, an edgeedge with one OSc6 octahedra, an edgeedge with one OSc4 tetrahedra, and edges with two equivalent OSc5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 11°.