SYNTHESIS AND CRYSTAL-STRUCTURE OF PB2SR2(LN,CE)NCU3O6+2N+DELTA AND PB(BA,SR)2(LN,CE)NCU3O5+2N+DELTA (LN=Y, N=3, 4, ... AND O-LESS-THAN-OR-EQUAL-TO-DELTA-LESS-THAN-OR-EQUAL-TO-2.0), LAYERED STRUCTURE COMPOUNDS WITH MULTIPLE FLUORITE LAYERS

Pb2Sr2(Ln,Ce)nCu3O6+2n+delta (Pb32n2) and Pb(Ba,Sr)2(Ln,Ce)nCu3O5+2n+delta (Pb22n2) (Ln = Y, n = 3, 4, ... and 0 less-than-or-equal-to delta less-than-or-equal-to 2.0) were synthesized and investigated by XPD, HREM, TGA and SEM-EDX. Almost-single phase of Pb2Sr2YCe2Cu3O12+delta (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.