Materials Data on BaTa2Bi2O9 by Materials Project

Abstract

BaBi2Ta2O9 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with four equivalent BaO12 cuboctahedra, faces with four equivalent BaO12 cuboctahedra, and faces with eight equivalent TaO6 octahedra. There are four shorter (2.81 Å) and eight longer (2.85 Å) Ba–O bond lengths. Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with five equivalent TaO6 octahedra and faces with four equivalent BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–10°. There are a spread of Ta–O bond distances ranging from 1.89–2.22 Å. Bi3+ is bonded in a 4-coordinate geometry to eight O2- atoms. There are four shorter (2.33 Å) and four longer (2.97 Å) Bi–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to two equivalent Ba2+ and two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded to four equivalent Bi3+ atoms to form a mixture of edge and corner-sharing OBi4 tetrahedra. In the third O2- site, O2- is bonded to four equivalent Ba2+ and two equivalent Ta5+ atoms to form a mixture of distorted edge and corner-sharing OBa4Ta2 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth O2- site, O2- is bonded in a single-bond geometry to one Ta5+ and four equivalent Bi3+ atoms.