Materials Data on KMg2AlFe(SiO4)3 by Materials Project
KMg2FeAl(SiO4)3 is Esseneite-derived structured and crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one KMg2FeAl(SiO4)3 sheet oriented in the (0, 0, 1) direction. K is bonded in a 12-coordinate geometry to three O atoms. There are a spread of K–O bond distances ranging from 2.77–2.81 Å. There are two 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 AlO4 tetrahedra, corners with three SiO4 tetrahedra, edges with three equivalent MgO6 octahedra, and edges with three equivalent FeO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.06–2.18 Å. In the second Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share a cornercorner with one AlO4 tetrahedra, corners with three SiO4 tetrahedra, edges with three equivalent MgO6 octahedra, and edges with three equivalent FeO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.06–2.18 Å. Fe is bonded to six O atoms to form FeO6 octahedra that share a cornercorner with one AlO4 tetrahedra, corners with three SiO4 tetrahedra, and edges with six MgO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.81–2.18 Å. Al is bonded to four O atoms to form AlO4 tetrahedra that share a cornercorner with one FeO6 octahedra, corners with two MgO6 octahedra, and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 60–62°. There are a spread of Al–O bond distances ranging from 1.73–1.78 Å. There are three inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one FeO6 octahedra, corners with two MgO6 octahedra, and corners with three equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 57–59°. There is three shorter (1.62 Å) and one longer (1.69 Å) Si–O bond length. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one FeO6 octahedra, corners with two MgO6 octahedra, and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–57°. There are a spread of Si–O bond distances ranging from 1.64–1.66 Å. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one FeO6 octahedra, corners with two MgO6 octahedra, and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–58°. There are a spread of Si–O bond distances ranging from 1.63–1.66 Å. There are twelve inequivalent O sites. In the first O site, O is bonded in a 2-coordinate geometry to one K, one Al, and one Si atom. In the second O site, O is bonded in a distorted bent 150 degrees geometry to two Si atoms. In the third O site, O is bonded in a 2-coordinate geometry to one K, one Al, and one Si atom. In the fourth O site, O is bonded in a 2-coordinate geometry to one K, one Al, and one Si atom. In the fifth O site, O is bonded in a distorted bent 150 degrees geometry to two Si atoms. In the sixth O site, O is bonded in a distorted bent 150 degrees geometry to two Si atoms. In the seventh O site, O is bonded to two Mg, one Fe, and one Al atom to form distorted corner-sharing OMg2AlFe tetrahedra. In the eighth O site, O is bonded to two Mg, one Fe, and one Si atom to form distorted corner-sharing OMg2FeSi trigonal pyramids. In the ninth O site, O is bonded in a distorted rectangular see-saw-like geometry to two Mg, one Fe, and one Si atom. In the tenth O site, O is bonded in a rectangular see-saw-like geometry to two Mg, one Fe, and one Si atom. In the eleventh O site, O is bonded in a trigonal non-coplanar geometry to two Mg and one Fe atom. In the twelfth O site, O is bonded in a distorted trigonal non-coplanar geometry to two Mg and one Fe atom.