Materials Data on Nb2Bi2PbO9 by Materials Project
PbBi2Nb2O9 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with five equivalent NbO6 octahedra and faces with four equivalent PbO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–11°. There are a spread of Nb–O bond distances ranging from 1.90–2.20 Å. Pb2+ is bonded to twelve O2- atoms to form PbO12 cuboctahedra that share corners with four equivalent PbO12 cuboctahedra, faces with four equivalent PbO12 cuboctahedra, and faces with eight equivalent NbO6 octahedra. There are four shorter (2.80 Å) and eight longer (2.82 Å) Pb–O bond lengths. Bi3+ is bonded in a 4-coordinate geometry to eight O2- atoms. There are four shorter (2.33 Å) and four longer (2.96 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 Nb5+ and two equivalent Pb2+ 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 in a distorted linear geometry to two equivalent Nb5+ and four equivalent Pb2+ atoms. In the fourth O2- site, O2- is bonded in a single-bond geometry to one Nb5+ and four equivalent Bi3+ atoms.