Materials Data on K3LuSi2O7 by Materials Project
K3LuSi2O7 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a distorted q6 geometry to nine equivalent O2- atoms. There are six shorter (2.88 Å) and three longer (3.05 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded in a 9-coordinate geometry to six equivalent O2- atoms. All K–O bond lengths are 2.81 Å. Lu3+ is bonded to six equivalent O2- atoms to form LuO6 octahedra that share corners with six equivalent SiO4 tetrahedra. All Lu–O bond lengths are 2.22 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent LuO6 octahedra and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 19°. There is three shorter (1.64 Å) and one longer (1.67 Å) Si–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to four K1+, one Lu3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a linear geometry to two equivalent Si4+ atoms.