DOE OSTI2020
MgTi2O4 is Spinel-like structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are six inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with three MgO6 octahedra and corners with nine TiO6 octahedra. The corner-sharing octahedra tilt angles range from 53–62°. All Mg–O bond lengths are 1.97 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six TiO4 tetrahedra, edges with two MgO6 octahedra, and edges with four TiO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.10–2.15 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO4 tetrahedra, corners with four TiO4 tetrahedra, an edgeedge with one MgO6 octahedra, and edges with five TiO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.06–2.18 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six TiO4 tetrahedra, edges with two MgO6 octahedra, and edges with four TiO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.09–2.20 Å. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six TiO4 tetrahedra, edges with two MgO6 octahedra, and edges with four equivalent TiO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.08–2.16 Å. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share a cornercorner with one MgO4 tetrahedra, corners with five TiO4 tetrahedra, an edgeedge with one MgO6 octahedra, and edges with five TiO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.05–2.16 Å. There are nine inequivalent Ti3+ sites. In the first Ti3+ site, Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two equivalent MgO4 tetrahedra, corners with four TiO4 tetrahedra, edges with three MgO6 octahedra, and edges with three TiO6 octahedra. There are a spread of Ti–O bond distances ranging from 1.98–2.19 Å. In the second Ti3+ site, Ti3+ is bonded to four O2- atoms to form TiO4 tetrahedra that share corners with six MgO6 octahedra and corners with six TiO6 octahedra. The corner-sharing octahedra tilt angles range from 51–59°. There are a spread of Ti–O bond distances ranging from 1.90–1.93 Å. In the third Ti3+ site, Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with three equivalent MgO4 tetrahedra, corners with three equivalent TiO4 tetrahedra, edges with two MgO6 octahedra, and edges with four TiO6 octahedra. There are a spread of Ti–O bond distances ranging from 2.07–2.16 Å. In the fourth Ti3+ site, Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO4 tetrahedra, edges with two equivalent TiO6 octahedra, and edges with four MgO6 octahedra. There are a spread of Ti–O bond distances ranging from 2.06–2.18 Å. In the fifth Ti3+ site, Ti3+ is bonded to four O2- atoms to form TiO4 tetrahedra that share corners with six MgO6 octahedra and corners with six TiO6 octahedra. The corner-sharing octahedra tilt angles range from 54–58°. There are a spread of Ti–O bond distances ranging from 1.88–1.91 Å. In the sixth Ti3+ site, Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one MgO4 tetrahedra, corners with five TiO4 tetrahedra, edges with three MgO6 octahedra, and edges with three TiO6 octahedra. There are a spread of Ti–O bond distances ranging from 2.04–2.23 Å. In the seventh Ti3+ site, Ti3+ is bonded to four O2- atoms to form TiO4 tetrahedra that share corners with six MgO6 octahedra and corners with six TiO6 octahedra. The corner-sharing octahedra tilt angles range from 53–60°. There is two shorter (1.89 Å) and two longer (1.91 Å) Ti–O bond length. In the eighth Ti3+ site, Ti3+ is bonded to four O2- atoms to form TiO4 tetrahedra that share corners with six MgO6 octahedra and corners with six TiO6 octahedra. The corner-sharing octahedra tilt angles range from 52–59°. There is two shorter (1.90 Å) and two longer (1.92 Å) Ti–O bond length. In the ninth Ti3+ site, Ti3+ is bonded to four O2- atoms to form TiO4 tetrahedra that share corners with three MgO6 octahedra and corners with nine TiO6 octahedra. The corner-sharing octahedra tilt angles range from 48–61°. There are a spread of Ti–O bond distances ranging from 1.86–1.89 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two Ti3+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ti3+ atoms. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ti3+ atoms. In the fourth O2- site, O2- is bonded to two Mg2+ and two Ti3+ atoms to form a mixture of distorted corner and edge-sharing OMg2Ti2 trigonal pyramids. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ti3+ atoms. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Ti3+ atoms. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two Ti3+ atoms. In the eighth O2- site, O2- is bonded in a distorted tetrahedral geometry to one Mg2+ and three Ti3+ atoms. In the ninth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Ti3+ atoms. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two Ti3+ atoms. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ti3+ atoms. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two Ti3+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted tetrahedral geometry to two Mg2+ and two equivalent Ti3+ atoms. In the fourteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ti3+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Ti3+ atoms. In the sixteenth O2- site, O2- is bonded in a 4-coordinate geometry to four Ti3+ atoms. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ti3+ atoms. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ti3+ atoms.