Layered Oxychlorides [PbBiO2]An+1BnO3n–1Cl2 (A = Pb/Bi, B = Fe/Ti): Intergrowth of the Hematophanite and Sillen Phases

New layered structures corresponding to the general formula [PbBiO2]An+1BnO3n–1Cl2 were prepared. Pb5BiFe3O10Cl2 (n = 3) and Pb5Bi2Fe4O13Cl2 (n = 4) are built as a stacking of truncated An+1BnO3n–1 perovskite blocks and α-PbO-type [A2O2]2+ (A = Pb, Bi) blocks combined with chlorine sheets. The alternation of these structural blocks can be represented as an intergrowth between the hematophanite and Sillen-type structural blocks. The crystal and magnetic structures of Pb5BiFe3O10Cl2 and Pb5Bi2Fe4O13Cl2 were investigated in the temperature range of 1.5–700 K using X-ray and neutron powder diffraction, transmission electron microscopy and 57Fe Mossbauer spectroscopy. Both compounds crystallize in the I4/mmm space group with the unit cell parameters a ≈ ap ≈ 3.92 A (a unit-cell parameter of the perovskite structure), c ≈ 43.0 A for the n = 3 member and c ≈ 53.5 A for the n = 4 member. Despite the large separation between the slabs containing the Fe3+ ions (nearly 14 A), long-range antiferromagnetic order sets ...