Materials Data on Be3Al2(SiO3)6 by Materials Project
Be3Al2Si6O18 crystallizes in the hexagonal P6/mcc space group. The structure is three-dimensional. Be2+ is bonded to four equivalent O2- atoms to form distorted BeO4 trigonal pyramids that share corners with four equivalent SiO4 tetrahedra and edges with two equivalent AlO6 octahedra. All Be–O bond lengths are 1.66 Å. Al3+ is bonded to six equivalent O2- atoms to form AlO6 octahedra that share corners with six equivalent SiO4 tetrahedra and edges with three equivalent BeO4 trigonal pyramids. All Al–O bond lengths are 1.93 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent AlO6 octahedra, corners with two equivalent SiO4 tetrahedra, and corners with two equivalent BeO4 trigonal pyramids. The corner-sharing octahedral tilt angles are 44°. There is two shorter (1.61 Å) and two longer (1.64 Å) Si–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Be2+, one Al3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a linear geometry to two equivalent Si4+ atoms.