DOE OSTI2020
Y3Se4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are six inequivalent Y sites. In the first Y site, Y is bonded to six Se atoms to form a mixture of edge and corner-sharing YSe6 octahedra. The corner-sharing octahedra tilt angles range from 1–4°. There are a spread of Y–Se bond distances ranging from 2.82–2.96 Å. In the second Y site, Y is bonded to six Se atoms to form a mixture of edge and corner-sharing YSe6 octahedra. The corner-sharing octahedral tilt angles are 2°. There are two shorter (2.86 Å) and four longer (2.88 Å) Y–Se bond lengths. In the third Y site, Y is bonded to six Se atoms to form a mixture of edge and corner-sharing YSe6 octahedra. The corner-sharing octahedral tilt angles are 2°. There are a spread of Y–Se bond distances ranging from 2.85–2.91 Å. In the fourth Y site, Y is bonded to six Se atoms to form a mixture of edge and corner-sharing YSe6 octahedra. The corner-sharing octahedra tilt angles range from 2–3°. There are a spread of Y–Se bond distances ranging from 2.86–2.89 Å. In the fifth Y site, Y is bonded to six Se atoms to form edge-sharing YSe6 octahedra. There are four shorter (2.86 Å) and two longer (2.89 Å) Y–Se bond lengths. In the sixth Y site, Y is bonded to six Se atoms to form a mixture of edge and corner-sharing YSe6 octahedra. The corner-sharing octahedra tilt angles range from 1–4°. There are a spread of Y–Se bond distances ranging from 2.85–2.90 Å. There are six inequivalent Se sites. In the first Se site, Se is bonded to five Y atoms to form SeY5 square pyramids that share corners with three equivalent SeY6 octahedra, corners with two equivalent SeY5 square pyramids, and edges with three equivalent SeY5 square pyramids. The corner-sharing octahedra tilt angles range from 3–4°. In the second Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the third Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the fourth Se site, Se is bonded to six Y atoms to form SeY6 octahedra that share corners with three equivalent SeY6 octahedra, corners with three equivalent SeY5 square pyramids, and an edgeedge with one SeY5 square pyramid. The corner-sharing octahedral tilt angles are 0°. In the fifth Se site, Se is bonded in a rectangular see-saw-like geometry to four Y atoms. In the sixth Se site, Se is bonded to five Y atoms to form SeY5 square pyramids that share corners with three equivalent SeY5 square pyramids, an edgeedge with one SeY6 octahedra, and edges with three equivalent SeY5 square pyramids.