Layered oxychlorides [PbBiO2]An+1BnO3n-1Cl2 (A = Pb/Bi, B = Fe/Ti): intergrowth of the hematophanite and Sillen phasesстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 17 ноября 2015 г.
Аннотация: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 that separate magnetic slabs of Fe3+ ions by nearly 14 Å. 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 Mössbauer spectroscopy. Both compounds crystalize in the I4/mmm space group with the unit cell parameters a ≈ ap ≈ 3.92 Å (a unit cell parameter of the perovskite structure), c ≈ 43.0 Å for the n = 3 member and c ≈ 53.5 Å for the n = 4 member. Despite the large separation between the slabs containing the Fe3+ ions, long-range antiferromagnetic order sets in below 600 K with the G-type arrangement of the Fe magnetic moments aligned along the c-axis. The possibility of mixing d0 and dn cations at the B sublattice of these structures was also demonstrated by preparing the Ti-substituted n = 4 member Pb6BiFe3TiO13Cl2.<i>