DOE OSTI2020
Sn2P2O7 crystallizes in the tetragonal P4_1 space group. The structure is three-dimensional. there are four inequivalent Sn2+ sites. In the first Sn2+ site, Sn2+ is bonded to six O2- atoms to form distorted SnO6 pentagonal pyramids that share corners with six PO4 tetrahedra and an edgeedge with one SnO6 octahedra. There are a spread of Sn–O bond distances ranging from 2.44–2.66 Å. In the second Sn2+ site, Sn2+ is bonded in a 5-coordinate geometry to six O2- atoms. There are a spread of Sn–O bond distances ranging from 2.39–2.84 Å. In the third Sn2+ site, Sn2+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of Sn–O bond distances ranging from 2.26–2.63 Å. In the fourth Sn2+ site, Sn2+ is bonded to six O2- atoms to form distorted SnO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one SnO6 pentagonal pyramid. There are a spread of Sn–O bond distances ranging from 2.44–2.70 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 a cornercorner with one SnO6 octahedra, a cornercorner with one SnO6 pentagonal pyramid, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. There are a spread of P–O bond distances ranging from 1.53–1.64 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent SnO6 octahedra, corners with two equivalent SnO6 pentagonal pyramids, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–67°. There are a spread of P–O bond distances ranging from 1.52–1.64 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent SnO6 octahedra, corners with two equivalent SnO6 pentagonal pyramids, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 60–62°. There are a spread of P–O bond distances ranging from 1.53–1.63 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one SnO6 octahedra, a cornercorner with one SnO6 pentagonal pyramid, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 60°. There are a spread of P–O bond distances ranging from 1.52–1.63 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two Sn2+ and one P5+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two Sn2+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to three Sn2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one Sn2+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two Sn2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to two Sn2+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to one Sn2+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms. In the ninth O2- site, O2- is bonded in a distorted single-bond geometry to two Sn2+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a distorted single-bond geometry to two Sn2+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted single-bond geometry to two Sn2+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted single-bond geometry to one Sn2+ and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sn2+ and one P5+ atom.