Materials Data on Mg3Ti3(AsO4)4 by Materials Project

Abstract

Mg3Ti3(AsO4)4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with two equivalent AsO4 tetrahedra, and edges with two equivalent TiO6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are a spread of Mg–O bond distances ranging from 2.00–2.30 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with four equivalent AsO4 tetrahedra and edges with two equivalent TiO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.11–2.21 Å. There are two inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with three equivalent AsO4 tetrahedra and edges with three MgO6 octahedra. There are a spread of Ti–O bond distances ranging from 1.76–2.23 Å. In the second Ti4+ site, Ti4+ is bonded in a distorted square co-planar geometry to four O2- atoms. There are two shorter (2.04 Å) and two longer (2.16 Å) Ti–O bond lengths. There are two inequivalent As+3.50+ sites. In the first As+3.50+ site, As+3.50+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with three equivalent TiO6 octahedra and corners with four MgO6 octahedra. The corner-sharing octahedra tilt angles range from 45–67°. There is one shorter (1.71 Å) and three longer (1.75 Å) As–O bond length. In the second As+3.50+ site, As+3.50+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of As–O bond distances ranging from 1.75–2.60 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+, two Ti4+, and one As+3.50+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Mg2+, one Ti4+, and one As+3.50+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Mg2+, one Ti4+, and one As+3.50+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Mg2+, one Ti4+, and one As+3.50+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Mg2+ and one As+3.50+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Mg2+, one Ti4+, and one As+3.50+ atom. In the seventh O2- site, O2- is bonded to one Mg2+, two Ti4+, and one As+3.50+ atom to form corner-sharing OMgTi2As tetrahedra. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Mg2+ and two As+3.50+ atoms.