DOE OSTI2020
MgV2O4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 pentagonal pyramids that share corners with six VO6 octahedra, edges with six VO6 octahedra, and edges with two equivalent MgO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 4–15°. There are a spread of Mg–O bond distances ranging from 2.11–2.26 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 pentagonal pyramids that share corners with six VO6 octahedra, edges with six VO6 octahedra, and edges with two equivalent MgO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 2–14°. There are a spread of Mg–O bond distances ranging from 2.14–2.24 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 pentagonal pyramids that share corners with twelve VO6 octahedra, edges with two equivalent MgO6 pentagonal pyramids, and faces with two VO6 octahedra. The corner-sharing octahedra tilt angles range from 45–52°. There are a spread of Mg–O bond distances ranging from 2.17–2.23 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 pentagonal pyramids that share corners with twelve VO6 octahedra, edges with two equivalent MgO6 pentagonal pyramids, and faces with two VO6 octahedra. The corner-sharing octahedra tilt angles range from 45–53°. There are a spread of Mg–O bond distances ranging from 2.17–2.23 Å. There are eight inequivalent V3+ sites. In the first V3+ site, V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with five MgO6 pentagonal pyramids, edges with six VO6 octahedra, an edgeedge with one MgO6 pentagonal pyramid, and a faceface with one MgO6 pentagonal pyramid. There are a spread of V–O bond distances ranging from 2.01–2.12 Å. In the second V3+ site, V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with five MgO6 pentagonal pyramids, edges with six VO6 octahedra, an edgeedge with one MgO6 pentagonal pyramid, and a faceface with one MgO6 pentagonal pyramid. There are a spread of V–O bond distances ranging from 2.01–2.12 Å. In the third V3+ site, V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with five MgO6 pentagonal pyramids, edges with six VO6 octahedra, an edgeedge with one MgO6 pentagonal pyramid, and a faceface with one MgO6 pentagonal pyramid. There are a spread of V–O bond distances ranging from 2.01–2.13 Å. In the fourth V3+ site, V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with five MgO6 pentagonal pyramids, edges with six VO6 octahedra, an edgeedge with one MgO6 pentagonal pyramid, and a faceface with one MgO6 pentagonal pyramid. There are a spread of V–O bond distances ranging from 2.01–2.12 Å. In the fifth V3+ site, V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with four MgO6 pentagonal pyramids, edges with six VO6 octahedra, and edges with two MgO6 pentagonal pyramids. There are a spread of V–O bond distances ranging from 1.99–2.11 Å. In the sixth V3+ site, V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with four MgO6 pentagonal pyramids, edges with six VO6 octahedra, and edges with two MgO6 pentagonal pyramids. There are a spread of V–O bond distances ranging from 2.00–2.11 Å. In the seventh V3+ site, V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with four MgO6 pentagonal pyramids, edges with six VO6 octahedra, and edges with two MgO6 pentagonal pyramids. There are a spread of V–O bond distances ranging from 2.00–2.11 Å. In the eighth V3+ site, V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with four MgO6 pentagonal pyramids, edges with six VO6 octahedra, and edges with two MgO6 pentagonal pyramids. There are a spread of V–O bond distances ranging from 1.99–2.11 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three V3+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three V3+ atoms. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three V3+ atoms. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three V3+ atoms. In the fifth O2- site, O2- is bonded to one Mg2+ and three V3+ atoms to form OMgV3 trigonal pyramids that share corners with four OMg2V3 trigonal bipyramids, corners with three OMgV3 trigonal pyramids, and edges with four OMg2V3 trigonal bipyramids. In the sixth O2- site, O2- is bonded to one Mg2+ and three V3+ atoms to form OMgV3 trigonal pyramids that share corners with four OMg2V3 trigonal bipyramids, corners with three OMgV3 trigonal pyramids, and edges with four OMg2V3 trigonal bipyramids. In the seventh O2- site, O2- is bonded to one Mg2+ and three V3+ atoms to form OMgV3 trigonal pyramids that share corners with four OMg2V3 trigonal bipyramids, corners with three OMgV3 trigonal pyramids, and edges with four OMg2V3 trigonal bipyramids. In the eighth O2- site, O2- is bonded to one Mg2+ and three V3+ atoms to form OMgV3 trigonal pyramids that share corners with four OMg2V3 trigonal bipyramids, corners with three OMgV3 trigonal pyramids, and edges with four OMg2V3 trigonal bipyramids. In the ninth O2- site, O2- is bonded to two Mg2+ and three V3+ atoms to form OMg2V3 trigonal bipyramids that share corners with five OMg2V3 trigonal bipyramids, corners with two OMgV3 trigonal pyramids, edges with four OMg2V3 trigonal bipyramids, and edges with two OMgV3 trigonal pyramids. In the tenth O2- site, O2- is bonded to two Mg2+ and three V3+ atoms to form OMg2V3 trigonal bipyramids that share corners with five OMg2V3 trigonal bipyramids, corners with two OMgV3 trigonal pyramids, edges with four OMg2V3 trigonal bipyramids, and edges with two OMgV3 trigonal pyramids. In the eleventh O2- site, O2- is bonded to two Mg2+ and three V3+ atoms to form OMg2V3 trigonal bipyramids that share corners with five OMg2V3 trigonal bipyramids, corners with two OMgV3 trigonal pyramids, edges with four OMg2V3 trigonal bipyramids, and edges with two OMgV3 trigonal pyramids. In the twelfth O2- site, O2- is bonded to two Mg2+ and three V3+ atoms to form OMg2V3 trigonal bipyramids that share corners with five OMg2V3 trigonal bipyramids, corners with two OMgV3 trigonal pyramids, edges with four OMg2V3 trigonal bipyramids, and edges with two OMgV3 trigonal pyramids. In the thirteenth O2- site, O2- is bonded to two Mg2+ and three V3+ atoms to form OMg2V3 trigonal bipyramids that share corners with five OMg2V3 trigonal bipyramids, corners with two OMgV3 trigonal pyramids, edges with four OMg2V3 trigonal bipyramids, and edges with two OMgV3 trigonal pyramids. In the fourteenth O2- site, O2- is bonded to two Mg2+ and three V3+ atoms to form OMg2V3 trigonal bipyramids that share corners with five OMg2V3 trigonal bipyramids, corners with two OMgV3 trigonal pyramids, edges with four OMg2V3 trigonal bipyramids, and edges with two OMgV3 trigonal pyramids. In the fifteenth O2- site, O2- is bonded to two Mg2+ and three V3+ atoms to form OMg2V3 trigonal bipyramids that share corners with five OMg2V3 trigonal bipyramids, corners with two OMgV3 trigonal pyramids, edges with four OMg2V3 trigonal bipyramids, and edges with two OMgV3 trigonal pyramids. In the sixteenth O2- site, O2- is bonded to two Mg2+ and three V3+ atoms to form OMg2V3 trigonal bipyramids that share corners with five OMg2V3 trigonal bipyramids, corners with two OMgV3 trigonal pyramids, edges with four OMg2V3 trigonal bipyramids, and edges with two OMgV3 trigonal pyramids.