Materials Data on PmSe3 by Materials Project
PmSe3 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pm3+ is bonded to twelve Se1- atoms to form distorted PmSe12 cuboctahedra that share corners with four equivalent PmSe12 cuboctahedra, edges with eight equivalent PmSe12 cuboctahedra, edges with sixteen equivalent SePm4Se8 cuboctahedra, faces with four equivalent PmSe12 cuboctahedra, and faces with eight equivalent SePm4Se8 cuboctahedra. There are four shorter (2.94 Å) and eight longer (3.40 Å) Pm–Se bond lengths. There are two inequivalent Se1- sites. In the first Se1- site, Se1- is bonded to four equivalent Pm3+ and eight Se1- atoms to form distorted SePm4Se8 cuboctahedra that share corners with twelve equivalent SePm4Se8 cuboctahedra, edges with eight equivalent PmSe12 cuboctahedra, edges with eight equivalent SePm4Se8 cuboctahedra, faces with four equivalent PmSe12 cuboctahedra, and faces with ten equivalent SePm4Se8 cuboctahedra. There are four shorter (2.94 Å) and four longer (3.40 Å) Se–Se bond lengths. In the second Se1- site, Se1- is bonded in a square co-planar geometry to four equivalent Pm3+ and eight equivalent Se1- atoms.