Materials Data on K3YbSi2O7 by Materials Project
K3YbSi2O7 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 6-coordinate geometry to six equivalent O2- atoms. All K–O bond lengths are 2.76 Å. In the second K1+ site, K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.83–3.04 Å. In the third K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are six shorter (2.96 Å) and three longer (3.06 Å) K–O bond lengths. There are two inequivalent Yb3+ sites. In the first Yb3+ site, Yb3+ is bonded to six equivalent O2- atoms to form distorted YbO6 pentagonal pyramids that share corners with six equivalent SiO4 tetrahedra. All Yb–O bond lengths are 2.37 Å. In the second Yb3+ site, Yb3+ is bonded to six equivalent O2- atoms to form YbO6 octahedra that share corners with six equivalent SiO4 tetrahedra. All Yb–O bond lengths are 2.30 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent YbO6 octahedra, a cornercorner with one YbO6 pentagonal pyramid, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 12°. There are a spread of Si–O bond distances ranging from 1.63–1.68 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+ and two equivalent Si4+ atoms. In the second O2- site, O2- is bonded in a 1-coordinate geometry to three K1+, one Yb3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 6-coordinate geometry to four K1+, one Yb3+, and one Si4+ atom.