DOE OSTI2020
Li9Fe4(PO5)4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are nine inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share corners with three FeO4 tetrahedra, corners with three PO4 tetrahedra, and corners with four LiO4 tetrahedra. There are a spread of Li–O bond distances ranging from 1.86–2.24 Å. In the second Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share corners with three FeO4 tetrahedra, corners with three PO4 tetrahedra, and corners with four LiO4 tetrahedra. There are a spread of Li–O bond distances ranging from 1.95–2.00 Å. In the third Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share a cornercorner with one FeO4 tetrahedra, corners with four PO4 tetrahedra, and corners with six LiO4 tetrahedra. There are a spread of Li–O bond distances ranging from 1.96–2.03 Å. In the fourth Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share corners with three LiO4 tetrahedra, corners with three PO4 tetrahedra, and corners with four FeO4 tetrahedra. There are a spread of Li–O bond distances ranging from 1.96–2.17 Å. In the fifth Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share corners with three FeO4 tetrahedra, corners with three PO4 tetrahedra, and corners with four LiO4 tetrahedra. There are a spread of Li–O bond distances ranging from 2.03–2.20 Å. In the sixth Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share corners with three FeO4 tetrahedra, corners with three PO4 tetrahedra, and corners with four LiO4 tetrahedra. There are a spread of Li–O bond distances ranging from 1.88–2.22 Å. In the seventh Li1+ site, Li1+ is bonded to four O2- atoms to form distorted LiO4 tetrahedra that share a cornercorner with one FeO4 tetrahedra, corners with four PO4 tetrahedra, and corners with five LiO4 tetrahedra. There are a spread of Li–O bond distances ranging from 2.02–2.27 Å. In the eighth Li1+ site, Li1+ is bonded to four O2- atoms to form distorted LiO4 tetrahedra that share a cornercorner with one FeO4 tetrahedra, corners with four PO4 tetrahedra, and corners with six LiO4 tetrahedra. There are a spread of Li–O bond distances ranging from 1.85–2.28 Å. In the ninth Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share corners with two equivalent LiO4 tetrahedra, corners with three PO4 tetrahedra, and corners with four FeO4 tetrahedra. There are a spread of Li–O bond distances ranging from 1.89–2.09 Å. There are four inequivalent Fe+2.75+ sites. In the first Fe+2.75+ site, Fe+2.75+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with two equivalent FeO4 tetrahedra, corners with two equivalent PO4 tetrahedra, and corners with six LiO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 1.94–2.12 Å. In the second Fe+2.75+ site, Fe+2.75+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with two equivalent FeO4 tetrahedra, corners with two equivalent PO4 tetrahedra, and corners with five LiO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 1.83–1.97 Å. In the third Fe+2.75+ site, Fe+2.75+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with two equivalent FeO4 tetrahedra, corners with two equivalent PO4 tetrahedra, and corners with six LiO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 1.86–1.96 Å. In the fourth Fe+2.75+ site, Fe+2.75+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with two equivalent FeO4 tetrahedra, corners with two equivalent PO4 tetrahedra, and corners with six LiO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 1.86–1.95 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent FeO4 tetrahedra and corners with seven LiO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.52–1.60 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent FeO4 tetrahedra and corners with eight LiO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.52–1.60 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent FeO4 tetrahedra and corners with eight LiO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.53–1.58 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent FeO4 tetrahedra and corners with seven LiO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. There are twenty inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to one Li1+, one Fe+2.75+, and one P5+ atom. In the second O2- site, O2- is bonded in a trigonal planar geometry to one Li1+, one Fe+2.75+, and one P5+ atom. In the third O2- site, O2- is bonded to two Li1+ and two Fe+2.75+ atoms to form corner-sharing OLi2Fe2 tetrahedra. In the fourth O2- site, O2- is bonded in a trigonal planar geometry to one Li1+ and two Fe+2.75+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Li1+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Li1+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two Li1+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Li1+ and one P5+ atom. In the ninth O2- site, O2- is bonded to two Li1+, one Fe+2.75+, and one P5+ atom to form corner-sharing OLi2FeP tetrahedra. In the tenth O2- site, O2- is bonded in a trigonal planar geometry to one Li1+, one Fe+2.75+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Fe+2.75+, and one P5+ atom. In the twelfth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Fe+2.75+, and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a trigonal planar geometry to one Li1+ and two Fe+2.75+ atoms. In the fourteenth O2- site, O2- is bonded to two Li1+ and two Fe+2.75+ atoms to form corner-sharing OLi2Fe2 tetrahedra. In the fifteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Li1+ and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Li1+ and one P5+ atom. In the seventeenth O2- site, O2- is bonded to three Li1+ and one P5+ atom to form corner-sharing OLi3P tetrahedra. In the eighteenth O2- site, O2- is bonded in a trigonal planar geometry to two Li1+ and one P5+ atom. In the nineteenth O2- site, O2- is bonded to two Li1+, one Fe+2.75+, and one P5+ atom to form distorted corner-sharing OLi2FeP tetrahedra. In the twentieth O2- site, O2- is bonded to two Li1+, one Fe+2.75+, and one P5+ atom to form distorted corner-sharing OLi2FeP tetrahedra.