Materials Data on Bi4Te2Br2O9 by Materials Project

Abstract

Bi4Te2O9Br2 crystallizes in the tetragonal P4mm space group. The structure is two-dimensional and consists of one Bi2O2Br sheet oriented in the (0, 0, 1) direction and one Te2O5 sheet oriented in the (0, 0, 1) direction. In the Bi2O2Br sheet, there are three inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded in a 4-coordinate geometry to four equivalent O2- and four equivalent Br1- atoms. All Bi–O bond lengths are 2.35 Å. All Bi–Br bond lengths are 3.30 Å. In the second Bi3+ site, Bi3+ is bonded in a 10-coordinate geometry to four equivalent O2- atoms. All Bi–O bond lengths are 2.36 Å. In the third Bi3+ site, Bi3+ is bonded in a 4-coordinate geometry to four equivalent O2- and four equivalent Br1- atoms. All Bi–O bond lengths are 2.34 Å. All Bi–Br bond lengths are 3.23 Å. O2- is bonded to four Bi3+ atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. Br1- is bonded in a 12-coordinate geometry to four Bi3+ atoms. In the Te2O5 sheet, there are two inequivalent Te4+ sites. In the first Te4+ site, Te4+ is bonded in a square pyramidal geometry to five O2- atoms. There are one shorter (1.91 Å) and four longer (2.10 Å) Te–O bond lengths. In the second Te4+ site, Te4+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Te–O bond lengths are 1.97 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two Te4+ atoms. In the second O2- site, O2- is bonded in a single-bond geometry to one Te4+ atom.