DOE OSTI2020
Ce2Co12P7 crystallizes in the hexagonal P-6 space group. The structure is three-dimensional. there are two inequivalent Ce3+ sites. In the first Ce3+ site, Ce3+ is bonded to six equivalent P3- atoms to form distorted CeP6 pentagonal pyramids that share corners with six equivalent CoP5 square pyramids, corners with twelve CoP4 tetrahedra, edges with twelve CoP4 tetrahedra, and faces with two equivalent CeP6 pentagonal pyramids. All Ce–P bond lengths are 2.91 Å. In the second Ce3+ site, Ce3+ is bonded to six equivalent P3- atoms to form distorted CeP6 pentagonal pyramids that share corners with six equivalent CoP5 square pyramids, corners with twelve CoP4 tetrahedra, edges with three equivalent CoP5 square pyramids, edges with nine CoP4 tetrahedra, and faces with two equivalent CeP6 pentagonal pyramids. All Ce–P bond lengths are 2.87 Å. There are four inequivalent Co+1.25+ sites. In the first Co+1.25+ site, Co+1.25+ is bonded to four P3- atoms to form CoP4 tetrahedra that share corners with two equivalent CeP6 pentagonal pyramids, corners with two equivalent CoP5 square pyramids, corners with twelve CoP4 tetrahedra, edges with three CeP6 pentagonal pyramids, edges with two equivalent CoP5 square pyramids, and edges with three CoP4 tetrahedra. There are a spread of Co–P bond distances ranging from 2.25–2.30 Å. In the second Co+1.25+ site, Co+1.25+ is bonded to four P3- atoms to form CoP4 tetrahedra that share corners with four CeP6 pentagonal pyramids, corners with two equivalent CoP5 square pyramids, corners with ten CoP4 tetrahedra, an edgeedge with one CeP6 pentagonal pyramid, edges with four equivalent CoP5 square pyramids, and edges with three CoP4 tetrahedra. There are a spread of Co–P bond distances ranging from 2.13–2.28 Å. In the third Co+1.25+ site, Co+1.25+ is bonded to four P3- atoms to form CoP4 tetrahedra that share corners with two equivalent CeP6 pentagonal pyramids, corners with four equivalent CoP5 square pyramids, corners with ten CoP4 tetrahedra, edges with three CeP6 pentagonal pyramids, an edgeedge with one CoP5 square pyramid, and edges with four CoP4 tetrahedra. There are a spread of Co–P bond distances ranging from 2.27–2.34 Å. In the fourth Co+1.25+ site, Co+1.25+ is bonded to five P3- atoms to form distorted CoP5 square pyramids that share corners with four CeP6 pentagonal pyramids, corners with four equivalent CoP5 square pyramids, corners with eight CoP4 tetrahedra, an edgeedge with one CeP6 pentagonal pyramid, edges with four equivalent CoP5 square pyramids, and edges with seven CoP4 tetrahedra. There are a spread of Co–P bond distances ranging from 2.22–2.52 Å. There are three inequivalent P3- sites. In the first P3- site, P3- is bonded in a 9-coordinate geometry to two equivalent Ce3+ and seven Co+1.25+ atoms. In the second P3- site, P3- is bonded in a 9-coordinate geometry to two equivalent Ce3+ and seven Co+1.25+ atoms. In the third P3- site, P3- is bonded in a 3-coordinate geometry to nine Co+1.25+ atoms.