Materials Data on Na5Gd4Si4O16F by Materials Project
Na5Gd4Si4O16F crystallizes in the tetragonal I-4 space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.40–2.87 Å. In the second Na1+ site, Na1+ is bonded in a distorted q6 geometry to eight O2- and two equivalent F1- atoms. There are four shorter (2.63 Å) and four longer (2.84 Å) Na–O bond lengths. Both Na–F bond lengths are 2.74 Å. Gd3+ is bonded in a 8-coordinate geometry to seven O2- and one F1- atom. There are a spread of Gd–O bond distances ranging from 2.31–2.58 Å. The Gd–F bond length is 2.57 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent FNa2Gd4O8 octahedra. The corner-sharing octahedra tilt angles range from 30–44°. There are a spread of Si–O bond distances ranging from 1.64–1.66 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+, two equivalent Gd3+, one Si4+, and one F1- atom. The O–F bond length is 2.81 Å. In the second O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two equivalent Gd3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 6-coordinate geometry to four equivalent Na1+, one Gd3+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+, two equivalent Gd3+, one Si4+, and one F1- atom. The O–F bond length is 2.72 Å. F1- is bonded to two equivalent Na1+, four equivalent Gd3+, and eight O2- atoms to form distorted FNa2Gd4O8 octahedra that share corners with two equivalent FNa2Gd4O8 octahedra and corners with eight equivalent SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 0°.