DOE OSTI2020
Pr2Co12P7 crystallizes in the hexagonal P-6 space group. The structure is three-dimensional. there are two inequivalent Pr3+ sites. In the first Pr3+ site, Pr3+ is bonded to six equivalent P3- atoms to form distorted PrP6 pentagonal pyramids that share corners with twelve CoP4 tetrahedra, edges with twelve CoP4 tetrahedra, and faces with two equivalent PrP6 pentagonal pyramids. All Pr–P bond lengths are 2.93 Å. In the second Pr3+ site, Pr3+ is bonded to six equivalent P3- atoms to form distorted PrP6 pentagonal pyramids that share corners with twelve CoP4 tetrahedra, edges with nine CoP4 tetrahedra, and faces with two equivalent PrP6 pentagonal pyramids. All Pr–P bond lengths are 2.90 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 PrP6 pentagonal pyramids, corners with twelve CoP4 tetrahedra, edges with three PrP6 pentagonal pyramids, and edges with three CoP4 tetrahedra. There are a spread of Co–P bond distances ranging from 2.28–2.31 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 two equivalent PrP6 pentagonal pyramids, corners with ten CoP4 tetrahedra, edges with three PrP6 pentagonal pyramids, and edges with four CoP4 tetrahedra. There are a spread of Co–P bond distances ranging from 2.26–2.37 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 four PrP6 pentagonal pyramids, corners with ten CoP4 tetrahedra, an edgeedge with one PrP6 pentagonal pyramid, and edges with three CoP4 tetrahedra. There are a spread of Co–P bond distances ranging from 2.12–2.30 Å. In the fourth Co+1.25+ site, Co+1.25+ is bonded in a 5-coordinate geometry to five P3- atoms. There are a spread of Co–P bond distances ranging from 2.21–2.56 Å. There are three inequivalent P3- sites. In the first P3- site, P3- is bonded in a 9-coordinate geometry to two equivalent Pr3+ and seven Co+1.25+ atoms. In the second P3- site, P3- is bonded in a 3-coordinate geometry to nine Co+1.25+ atoms. In the third P3- site, P3- is bonded in a 9-coordinate geometry to two equivalent Pr3+ and seven Co+1.25+ atoms.