DOE OSTI2020
Li2FeP2O7 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 1.98–2.43 Å. In the second Li1+ site, Li1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Li–O bond distances ranging from 1.96–2.71 Å. In the third Li1+ site, Li1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Li–O bond distances ranging from 2.01–2.46 Å. In the fourth Li1+ site, Li1+ is bonded to four O2- atoms to form distorted LiO4 trigonal pyramids that share a cornercorner with one FeO6 octahedra and corners with four PO4 tetrahedra. The corner-sharing octahedral tilt angles are 34°. There are a spread of Li–O bond distances ranging from 1.97–2.15 Å. In the fifth Li1+ site, Li1+ is bonded in a distorted see-saw-like geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 1.93–2.13 Å. In the sixth Li1+ site, Li1+ is bonded to five O2- atoms to form distorted LiO5 trigonal bipyramids that share corners with five PO4 tetrahedra, an edgeedge with one FeO6 octahedra, and a faceface with one FeO6 octahedra. There are a spread of Li–O bond distances ranging from 2.00–2.34 Å. In the seventh Li1+ site, Li1+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. There are a spread of Li–O bond distances ranging from 1.97–2.23 Å. In the eighth Li1+ site, Li1+ is bonded in a 3-coordinate geometry to five O2- atoms. There are a spread of Li–O bond distances ranging from 2.00–2.77 Å. There are four inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one FeO6 octahedra, corners with six PO4 tetrahedra, and a faceface with one LiO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 66°. There are a spread of Fe–O bond distances ranging from 2.08–2.21 Å. In the second Fe2+ site, Fe2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Fe–O bond distances ranging from 2.05–2.53 Å. In the third Fe2+ site, Fe2+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one LiO5 trigonal bipyramid. There are a spread of Fe–O bond distances ranging from 2.08–2.25 Å. In the fourth Fe2+ site, Fe2+ is bonded to six O2- atoms to form distorted FeO6 octahedra that share a cornercorner with one FeO6 octahedra, corners with four PO4 tetrahedra, a cornercorner with one LiO4 trigonal pyramid, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 66°. There are a spread of Fe–O bond distances ranging from 2.07–2.49 Å. There are eight inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two FeO6 octahedra, a cornercorner with one PO4 tetrahedra, and a cornercorner with one LiO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 50–54°. There are a spread of P–O bond distances ranging from 1.52–1.66 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two FeO6 octahedra, a cornercorner with one PO4 tetrahedra, and a cornercorner with one LiO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 39–57°. There are a spread of P–O bond distances ranging from 1.51–1.65 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two FeO6 octahedra, a cornercorner with one PO4 tetrahedra, a cornercorner with one LiO5 trigonal bipyramid, and a cornercorner with one LiO4 trigonal pyramid. The corner-sharing octahedra tilt angles range from 44–47°. There are a spread of P–O bond distances ranging from 1.52–1.64 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three FeO6 octahedra, a cornercorner with one PO4 tetrahedra, and a cornercorner with one LiO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 38–58°. There are a spread of P–O bond distances ranging from 1.52–1.63 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two FeO6 octahedra, a cornercorner with one PO4 tetrahedra, and a cornercorner with one LiO4 trigonal pyramid. The corner-sharing octahedra tilt angles range from 56–57°. There are a spread of P–O bond distances ranging from 1.52–1.61 Å. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two FeO6 octahedra, a cornercorner with one PO4 tetrahedra, a cornercorner with one LiO4 trigonal pyramid, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 55–56°. There are a spread of P–O bond distances ranging from 1.52–1.61 Å. In the seventh P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent FeO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 34–59°. There are a spread of P–O bond distances ranging from 1.51–1.62 Å. In the eighth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one FeO6 octahedra, a cornercorner with one PO4 tetrahedra, a cornercorner with one LiO5 trigonal bipyramid, and a cornercorner with one LiO4 trigonal pyramid. The corner-sharing octahedral tilt angles are 50°. There are a spread of P–O bond distances ranging from 1.51–1.66 Å. There are twenty-eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Fe2+, and one P5+ atom. In the second O2- site, O2- is bonded in a 5-coordinate geometry to two Li1+, one Fe2+, and one P5+ atom. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Li1+, one Fe2+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Fe2+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two P5+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe2+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to two Li1+, one Fe2+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe2+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a trigonal planar geometry to one Li1+, one Fe2+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe2+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the twelfth O2- site, O2- is bonded in a 5-coordinate geometry to three Li1+, one Fe2+, and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Li1+, one Fe2+, and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe2+, and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Fe2+, and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Li1+, one Fe2+, and one P5+ atom. In the seventeenth O2- site, O2- is bonded in a 4-coordinate geometry to three Li1+ and one P5+ atom. In the eighteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+ and two P5+ atoms. In the nineteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe2+, and one P5+ atom. In the twentieth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Li1+ and one P5+ atom. In the twenty-first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Fe2+ and one P5+ atom. In the twenty-second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Fe2+, and one P5+ atom. In the twenty-third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Fe2+ and one P5+ atom. In the twenty-fourth O2- site, O2- is bonded in a trigonal planar geometry to one Li1+, one Fe2+, and one P5+ atom. In the twenty-fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Fe2+, and one P5+ atom. In the twenty-sixth O2- site, O2- is bonded in a 1-coordinate geometry to one Li1+, two Fe2+, and one P5+ atom. In the twenty-seventh O2- site, O2- is bonded in a 4-coordinate geometry to two Li1+, one Fe2+, and one P5+ atom. In the twenty-eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+ and two P5+ atoms.