Synthesis and crystal structure of Pb₂Sr₂(Ln,Ce)_nCu₃O_6+2n+δ and Pb(Ba,Sr)₂(Ln,Ce)_nCu₃O_5+2n+δ (Ln=Y,n=3,4,... and 0≤δ≤2.0), layered structure compounds with multiple fluorite layers

Pb₂Sr₂(Ln,Ce)_nCu₃O_6+2n+δ (Pb32n2) and Pb(Ba,Sr)₂(Ln,Ce)_nCu₃O_5+2n+δ (Pb22n2) (Ln=Y, n=3, 4, ... and 0≤δ≤2.0) were synthesized and investigated by XPD, HREM, TGA and SEM-EDX. Almost-single phase of Pb₂Sr₂YCe₂Cu₃O_12+δ (Pb3232) was prepared using a gel-citric acid method, although it was not obtained through a solid state reaction. The crystal structure of Pb32n2 and Pb22n2, which was studied by XPD analysis and HREM, was found to be layered constructed by stacking of (Pb, Cu) triple or double layers and (Ln, Ce) multiple fluorite layers. These compounds showed a phase transition accompanied with oxygen absorption and desorption, similar to Pb3212 and Pb3222. SEM observation and EDX analysis of sintered surface indicated that homogeneous dispersion of CeO₂ led the products to intergrowth structure of Pb32n2 and Pb22n2 (n = 3, 4, ...) with multiple fluorite layers.