Materials Data on Ca3Fe2Br2O5 by Materials Project
Ca3Fe2O5Br2 crystallizes in the tetragonal I4/mmm space group. The structure is two-dimensional and consists of two Ca3Fe2O5Br2 sheets oriented in the (0, 0, 1) direction. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 4-coordinate geometry to four equivalent O2- and four equivalent Br1- atoms. All Ca–O bond lengths are 2.42 Å. All Ca–Br bond lengths are 3.10 Å. In the second Ca2+ site, Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share corners with four equivalent CaO12 cuboctahedra, faces with four equivalent CaO12 cuboctahedra, and faces with eight equivalent FeBrO5 square pyramids. There are four shorter (2.78 Å) and eight longer (2.95 Å) Ca–O bond lengths. Fe3+ is bonded to five O2- and one Br1- atom to form distorted FeBrO5 square pyramids that share corners with five equivalent FeBrO5 square pyramids and faces with four equivalent CaO12 cuboctahedra. There is one shorter (1.94 Å) and four longer (1.98 Å) Fe–O bond length. The Fe–Br bond length is 3.05 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to four Ca2+ and two equivalent Fe3+ atoms. In the second O2- site, O2- is bonded to four equivalent Ca2+ and two equivalent Fe3+ atoms to form a mixture of distorted edge and corner-sharing OCa4Fe2 octahedra. The corner-sharing octahedral tilt angles are 0°. Br1- is bonded in a 5-coordinate geometry to four equivalent Ca2+ and one Fe3+ atom.