DOE OSTI2020
FePSe crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Fe3+ is bonded to three equivalent P1- and three equivalent Se2- atoms to form FeP3Se3 octahedra that share corners with eight equivalent FeP3Se3 octahedra, corners with three equivalent PFe3Se tetrahedra, corners with three equivalent SeFe3P tetrahedra, and edges with two equivalent FeP3Se3 octahedra. The corner-sharing octahedra tilt angles range from 54–59°. There are one shorter (2.29 Å) and two longer (2.30 Å) Fe–P bond lengths. There are a spread of Fe–Se bond distances ranging from 2.32–2.34 Å. P1- is bonded to three equivalent Fe3+ and one Se2- atom to form distorted PFe3Se tetrahedra that share corners with three equivalent FeP3Se3 octahedra, corners with four equivalent PFe3Se tetrahedra, corners with nine equivalent SeFe3P tetrahedra, and an edgeedge with one PFe3Se tetrahedra. The corner-sharing octahedra tilt angles range from 66–73°. The P–Se bond length is 2.42 Å. Se2- is bonded to three equivalent Fe3+ and one P1- atom to form distorted SeFe3P tetrahedra that share corners with three equivalent FeP3Se3 octahedra, corners with four equivalent SeFe3P tetrahedra, corners with nine equivalent PFe3Se tetrahedra, and an edgeedge with one SeFe3P tetrahedra. The corner-sharing octahedra tilt angles range from 74–81°.