Materials Data on EuTa3O9 by Materials Project
EuTa3O9 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Eu3+ is bonded to twelve O2- atoms to form EuO12 cuboctahedra that share corners with three equivalent EuO12 cuboctahedra, faces with two equivalent EuO12 cuboctahedra, and faces with eight TaO6 octahedra. There are a spread of Eu–O bond distances ranging from 2.65–2.80 Å. There are three inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and faces with three equivalent EuO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–16°. There are a spread of Ta–O bond distances ranging from 1.93–2.06 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and faces with two equivalent EuO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–13°. There are a spread of Ta–O bond distances ranging from 1.96–2.01 Å. In the third Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and faces with three equivalent EuO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 2–16°. There are a spread of Ta–O bond distances ranging from 1.91–2.08 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to two equivalent Eu3+ and two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Eu3+ and two Ta5+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Eu3+ and two Ta5+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Eu3+ and two Ta5+ atoms. In the fifth O2- site, O2- is bonded in a linear geometry to two equivalent Ta5+ atoms. In the sixth O2- site, O2- is bonded in a linear geometry to two Ta5+ atoms. In the seventh O2- site, O2- is bonded in a distorted linear geometry to three equivalent Eu3+ and two Ta5+ atoms.