DOE OSTI2020
Na6Cu9(PO4)8 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.32–2.91 Å. In the second Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.24–2.45 Å. In the third Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.36–3.03 Å. There are six inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded to five O2- atoms to form distorted CuO5 square pyramids that share corners with three PO4 tetrahedra and an edgeedge with one PO4 tetrahedra. There are a spread of Cu–O bond distances ranging from 1.91–2.44 Å. In the second Cu2+ site, Cu2+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Cu–O bond distances ranging from 1.94–2.05 Å. In the third Cu2+ site, Cu2+ is bonded to five O2- atoms to form distorted CuO5 trigonal bipyramids that share corners with five PO4 tetrahedra. There are a spread of Cu–O bond distances ranging from 1.93–2.54 Å. In the fourth Cu2+ site, Cu2+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.95 Å) and two longer (2.02 Å) Cu–O bond length. In the fifth Cu2+ site, Cu2+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.00 Å) and two longer (2.02 Å) Cu–O bond lengths. In the sixth Cu2+ site, Cu2+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.98 Å) and two longer (2.00 Å) Cu–O bond length. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CuO5 square pyramid and a cornercorner with one CuO5 trigonal bipyramid. There are a spread of P–O bond distances ranging from 1.55–1.57 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CuO5 square pyramid and corners with two equivalent CuO5 trigonal bipyramids. There are a spread of P–O bond distances ranging from 1.54–1.60 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CuO5 trigonal bipyramid and an edgeedge with one CuO5 square pyramid. There are a spread of P–O bond distances ranging from 1.54–1.59 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CuO5 square pyramid and a cornercorner with one CuO5 trigonal bipyramid. There are a spread of P–O bond distances ranging from 1.55–1.57 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, two Cu2+, and one P5+ atom. In the second O2- site, O2- is bonded to two Na1+, one Cu2+, and one P5+ atom to form distorted corner-sharing ONa2CuP tetrahedra. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+, one Cu2+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two Cu2+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two Cu2+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na1+, one Cu2+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two Cu2+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+, one Cu2+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Cu2+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Cu2+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Cu2+, and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Cu2+, and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Cu2+, and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cu2+ and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Cu2+, and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Cu2+, and one P5+ atom.