Materials Data on KMg3AlSi3(HO6)2 by Materials Project
KAlMg3Si3O10(OH)2 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one KAlMg3Si3O10(OH)2 sheet oriented in the (0, 0, 1) direction. K1+ is bonded in a 4-coordinate geometry to three O2- atoms. There are one shorter (2.76 Å) and two longer (2.79 Å) K–O bond lengths. There are three inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 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 Mg–O bond distances ranging from 2.02–2.19 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 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 Mg–O bond distances ranging from 2.02–2.16 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 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 Mg–O bond distances ranging from 2.02–2.17 Å. Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with three MgO6 octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 61°. There is one shorter (1.75 Å) and three longer (1.77 Å) Al–O bond length. There are three inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three MgO6 octahedra and corners with three equivalent AlO4 tetrahedra. The corner-sharing octahedral tilt angles are 58°. There is three shorter (1.64 Å) and one longer (1.67 Å) Si–O bond length. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three MgO6 octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–57°. There is one shorter (1.61 Å) and three longer (1.67 Å) Si–O bond length. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three MgO6 octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–57°. There is one shorter (1.61 Å) and three longer (1.67 Å) Si–O bond length. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded to three Mg2+ and one Al3+ atom to form distorted corner-sharing OMg3Al tetrahedra. In the second O2- site, O2- is bonded to three Mg2+ and one Si4+ atom to form distorted corner-sharing OMg3Si trigonal pyramids. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Mg2+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Al3+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Si4+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Al3+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Al3+, and one Si4+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Si4+ atoms. In the tenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Si4+ atoms. In the eleventh O2- site, O2- is bonded in a 1-coordinate geometry to three Mg2+ and one H1+ atom. In the twelfth O2- site, O2- is bonded in a distorted single-bond geometry to three Mg2+ and one H1+ atom.