DOE OSTI2020
Sm2Cr2O5 crystallizes in the orthorhombic Ima2 space group. The structure is three-dimensional. Sm3+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Sm–O bond distances ranging from 2.22–2.49 Å. There are two inequivalent Cr2+ sites. In the first Cr2+ site, Cr2+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with four equivalent CrO6 octahedra and corners with two equivalent CrO4 trigonal pyramids. The corner-sharing octahedral tilt angles are 27°. There are two shorter (2.02 Å) and four longer (2.03 Å) Cr–O bond lengths. In the second Cr2+ site, Cr2+ is bonded to four O2- atoms to form distorted CrO4 trigonal pyramids that share corners with two equivalent CrO6 octahedra and corners with two equivalent CrO4 trigonal pyramids. The corner-sharing octahedral tilt angles are 34°. There are a spread of Cr–O bond distances ranging from 2.08–2.32 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Sm3+ and two equivalent Cr2+ atoms. In the second O2- site, O2- is bonded to two equivalent Sm3+ and two Cr2+ atoms to form distorted corner-sharing OSm2Cr2 tetrahedra. In the third O2- site, O2- is bonded to two equivalent Sm3+ and two equivalent Cr2+ atoms to form corner-sharing OSm2Cr2 tetrahedra.