Materials Data on Sm2Ta2O9 by Materials Project
Sm2Ta2O9 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Sm is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Sm–O bond distances ranging from 2.33–2.60 Å. Ta is bonded to six O atoms to form a mixture of distorted corner and edge-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 0–15°. There are a spread of Ta–O bond distances ranging from 1.90–2.20 Å. There are five inequivalent O sites. In the first O site, O is bonded to two equivalent Sm and two equivalent Ta atoms to form a mixture of distorted corner and edge-sharing OSm2Ta2 trigonal pyramids. In the second O site, O is bonded in a distorted trigonal planar geometry to three equivalent Sm atoms. In the third O site, O is bonded in a linear geometry to two equivalent Ta atoms. In the fourth O site, O is bonded in a distorted T-shaped geometry to one Sm and two equivalent Ta atoms. In the fifth O site, O is bonded in a 4-coordinate geometry to three equivalent Sm and one Ta atom.