Materials Data on La2Ta2O9 by Materials Project
La2Ta2O9 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. La is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of La–O bond distances ranging from 2.42–2.65 Å. Ta is bonded to six O atoms to form a mixture of distorted edge and corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 0–13°. There are a spread of Ta–O bond distances ranging from 1.92–2.22 Å. There are five inequivalent O sites. In the first O site, O is bonded in a distorted rectangular see-saw-like geometry to two equivalent La and two equivalent Ta atoms. In the second O site, O is bonded in a distorted T-shaped geometry to one La and two equivalent Ta 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 4-coordinate geometry to three equivalent La and one Ta atom. In the fifth O site, O is bonded in a distorted trigonal planar geometry to three equivalent La atoms.