DOE OSTI2020
EuP7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Eu3+ is bonded in a 9-coordinate geometry to nine P+0.43- atoms. There are a spread of Eu–P bond distances ranging from 3.08–3.27 Å. There are seven inequivalent P+0.43- sites. In the first P+0.43- site, P+0.43- is bonded to one Eu3+ and three P+0.43- atoms to form PEuP3 tetrahedra that share corners with ten PEu2P2 tetrahedra and a cornercorner with one PEuP3 trigonal pyramid. There are a spread of P–P bond distances ranging from 2.20–2.27 Å. In the second P+0.43- site, P+0.43- is bonded to one Eu3+ and three P+0.43- atoms to form distorted PEuP3 trigonal pyramids that share corners with eight PEuP3 tetrahedra and an edgeedge with one PEu2P2 tetrahedra. There are a spread of P–P bond distances ranging from 2.21–2.26 Å. In the third P+0.43- site, P+0.43- is bonded in a see-saw-like geometry to one Eu3+ and three P+0.43- atoms. There are one shorter (2.22 Å) and one longer (2.23 Å) P–P bond lengths. In the fourth P+0.43- site, P+0.43- is bonded to two equivalent Eu3+ and two P+0.43- atoms to form a mixture of edge and corner-sharing PEu2P2 tetrahedra. The P–P bond length is 2.22 Å. In the fifth P+0.43- site, P+0.43- is bonded to one Eu3+ and three P+0.43- atoms to form distorted PEuP3 tetrahedra that share corners with eight PEuP3 tetrahedra, corners with two equivalent PEuP3 trigonal pyramids, and an edgeedge with one PEu2P2 tetrahedra. The P–P bond length is 2.23 Å. In the sixth P+0.43- site, P+0.43- is bonded to two equivalent Eu3+ and two P+0.43- atoms to form a mixture of edge and corner-sharing PEu2P2 tetrahedra. In the seventh P+0.43- site, P+0.43- is bonded to one Eu3+ and three P+0.43- atoms to form distorted corner-sharing PEuP3 tetrahedra.