DOE OSTI2020
MgTiP2O7 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Mg2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Mg–O bond distances ranging from 2.05–2.47 Å. Ti2+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one TiO6 octahedra. There are a spread of Ti–O bond distances ranging from 2.10–2.55 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent TiO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–57°. There is three shorter (1.54 Å) and one longer (1.59 Å) P–O bond length. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent TiO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–60°. There are a spread of P–O bond distances ranging from 1.52–1.64 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Mg2+, one Ti2+, and one P5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+, one Ti2+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Mg2+, one Ti2+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Mg2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ti2+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Ti2+ and one P5+ atom.