DOE OSTI2020
MgO6Mg7W9SiO43 crystallizes in the monoclinic Cc space group. The structure is three-dimensional and consists of four magnesium;dihydroxide;tetrahydrate molecules and one Mg7W9SiO43 framework. In the Mg7W9SiO43 framework, there are three inequivalent Mg sites. In the first Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share a cornercorner with one SiO4 tetrahedra and edges with two equivalent MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.03–2.13 Å. In the second Mg site, Mg is bonded to five O atoms to form distorted corner-sharing MgO5 trigonal bipyramids. There are a spread of Mg–O bond distances ranging from 1.98–2.14 Å. In the third Mg site, Mg is bonded in a distorted hexagonal planar geometry to six O atoms. There are three shorter (2.02 Å) and three longer (2.05 Å) Mg–O bond lengths. There are three inequivalent W sites. In the first W site, W is bonded in a 6-coordinate geometry to six O atoms. There are a spread of W–O bond distances ranging from 1.78–2.42 Å. In the second W site, W is bonded in a 6-coordinate geometry to six O atoms. There are a spread of W–O bond distances ranging from 1.78–2.42 Å. In the third W site, W is bonded in a 6-coordinate geometry to six O atoms. There are a spread of W–O bond distances ranging from 1.78–2.37 Å. Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 58°. There is one shorter (1.63 Å) and three longer (1.67 Å) Si–O bond length. There are forty-one inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. The O–Mg bond length is 1.98 Å. In the second O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. The O–Mg bond length is 1.98 Å. The O–W bond length is 1.78 Å. In the third O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. The O–W bond length is 1.78 Å. In the fourth O site, O is bonded in a bent 120 degrees geometry to two W atoms. In the fifth O site, O is bonded in a bent 120 degrees geometry to two W atoms. There is one shorter (1.92 Å) and one longer (2.01 Å) O–W bond length. In the sixth O site, O is bonded in a bent 120 degrees geometry to two W atoms. There is one shorter (1.92 Å) and one longer (2.01 Å) O–W bond length. In the seventh O site, O is bonded in a T-shaped geometry to three Mg atoms. In the eighth O site, O is bonded in a T-shaped geometry to three Mg atoms. In the ninth O site, O is bonded in a T-shaped geometry to three Mg atoms. There are one shorter (2.13 Å) and one longer (2.14 Å) O–Mg bond lengths. In the tenth O site, O is bonded in a single-bond geometry to one Mg atom. In the eleventh O site, O is bonded in a single-bond geometry to one Mg atom. The O–Mg bond length is 2.13 Å. In the twelfth O site, O is bonded in a distorted single-bond geometry to three W and one Si atom. In the thirteenth O site, O is bonded in a distorted single-bond geometry to three W and one Si atom. There are one shorter (2.37 Å) and two longer (2.42 Å) O–W bond lengths. In the fourteenth O site, O is bonded in a distorted single-bond geometry to three W and one Si atom. There are one shorter (2.37 Å) and two longer (2.42 Å) O–W bond lengths. In the fifteenth O site, O is bonded in a distorted trigonal pyramidal geometry to three equivalent Mg and one Si atom. In the sixteenth O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. The O–Mg bond length is 2.01 Å. The O–W bond length is 1.78 Å. In the seventeenth O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. In the eighteenth O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. The O–Mg bond length is 2.01 Å. The O–W bond length is 1.78 Å. In the nineteenth O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. The O–Mg bond length is 2.01 Å. In the twentieth O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. The O–W bond length is 1.78 Å. In the twenty-first O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. The O–Mg bond length is 2.01 Å. The O–W bond length is 1.78 Å. In the twenty-second O site, O is bonded in a bent 120 degrees geometry to two W atoms. In the twenty-third O site, O is bonded in a bent 120 degrees geometry to two W atoms. Both O–W bond lengths are 2.03 Å. In the twenty-fourth O site, O is bonded in a bent 120 degrees geometry to two W atoms. Both O–W bond lengths are 2.03 Å. In the twenty-fifth O site, O is bonded in a bent 150 degrees geometry to two W atoms. The O–W bond length is 1.93 Å. In the twenty-sixth O site, O is bonded in a bent 150 degrees geometry to two W atoms. Both O–W bond lengths are 1.93 Å. In the twenty-seventh O site, O is bonded in a bent 150 degrees geometry to two W atoms. The O–W bond length is 1.93 Å. In the twenty-eighth O site, O is bonded in a bent 120 degrees geometry to two W atoms. In the twenty-ninth O site, O is bonded in a bent 120 degrees geometry to two W atoms. There is one shorter (1.92 Å) and one longer (2.01 Å) O–W bond length. In the thirtieth O site, O is bonded in a bent 120 degrees geometry to two W atoms. There is one shorter (1.92 Å) and one longer (2.01 Å) O–W bond length. In the thirty-first O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. The O–Mg bond length is 2.03 Å. In the thirty-second O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. The O–Mg bond length is 2.03 Å. The O–W bond length is 1.82 Å. In the thirty-third O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. The O–W bond length is 1.82 Å. In the thirty-fourth O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. In the thirty-fifth O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. The O–Mg bond length is 2.03 Å. The O–W bond length is 1.82 Å. In the thirty-sixth O site, O is bonded in a bent 150 degrees geometry to one Mg and one W atom. The O–Mg bond length is 2.03 Å. The O–W bond length is 1.82 Å. In the thirty-seventh O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms. In the thirty-eighth O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms. Both O–Mg bond lengths are 2.12 Å. In the thirty-ninth O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms. In the fortieth O site, O is bonded in a bent 150 degrees geometry to two equivalent W atoms. In the forty-first O site, O is bonded in a bent 150 degrees geometry to two equivalent W atoms.