DOE OSTI2020
Pr2O3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Pr3+ sites. In the first Pr3+ site, Pr3+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing PrO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Pr–O bond distances ranging from 2.33–2.64 Å. In the second Pr3+ site, Pr3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Pr–O bond distances ranging from 2.37–2.86 Å. In the third Pr3+ site, Pr3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Pr–O bond distances ranging from 2.37–2.80 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to five Pr3+ atoms to form distorted OPr5 square pyramids that share corners with seven OPr4 tetrahedra, corners with two equivalent OPr4 trigonal pyramids, edges with two equivalent OPr6 octahedra, edges with two equivalent OPr5 square pyramids, edges with three OPr4 tetrahedra, and edges with three equivalent OPr4 trigonal pyramids. In the second O2- site, O2- is bonded to four Pr3+ atoms to form OPr4 tetrahedra that share a cornercorner with one OPr6 octahedra, corners with five equivalent OPr5 square pyramids, corners with four OPr4 tetrahedra, corners with three equivalent OPr4 trigonal pyramids, edges with two equivalent OPr6 octahedra, an edgeedge with one OPr5 square pyramid, and edges with two equivalent OPr4 tetrahedra. The corner-sharing octahedral tilt angles are 51°. In the third O2- site, O2- is bonded to four Pr3+ atoms to form OPr4 tetrahedra that share corners with two equivalent OPr6 octahedra, corners with two equivalent OPr5 square pyramids, corners with four OPr4 tetrahedra, corners with six equivalent OPr4 trigonal pyramids, an edgeedge with one OPr6 octahedra, edges with two equivalent OPr5 square pyramids, and an edgeedge with one OPr4 tetrahedra. The corner-sharing octahedral tilt angles are 15°. In the fourth O2- site, O2- is bonded to four Pr3+ atoms to form distorted OPr4 trigonal pyramids that share a cornercorner with one OPr6 octahedra, corners with two equivalent OPr5 square pyramids, corners with nine OPr4 tetrahedra, corners with two equivalent OPr4 trigonal pyramids, edges with three equivalent OPr5 square pyramids, and edges with two equivalent OPr4 trigonal pyramids. The corner-sharing octahedral tilt angles are 35°. In the fifth O2- site, O2- is bonded to six Pr3+ atoms to form OPr6 octahedra that share corners with six OPr4 tetrahedra, corners with two equivalent OPr4 trigonal pyramids, edges with two equivalent OPr6 octahedra, edges with four equivalent OPr5 square pyramids, and edges with six OPr4 tetrahedra.