Materials Data on CaTa2Bi2O9 by Materials Project

Abstract

CaBi2Ta2O9 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.38–2.61 Å. Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 25–31°. There are a spread of Ta–O bond distances ranging from 1.90–2.11 Å. Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.20–2.57 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Ta5+ and two equivalent Bi3+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two equivalent Ta5+ atoms. In the third O2- site, O2- is bonded to two equivalent Ca2+ and two equivalent Ta5+ atoms to form distorted corner-sharing OCa2Ta2 tetrahedra. In the fourth O2- site, O2- is bonded to four equivalent Bi3+ atoms to form a mixture of distorted corner and edge-sharing OBi4 tetrahedra. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ca2+ and two equivalent Ta5+ atoms.