SYNTHESIS AND CRYSTAL-STRUCTURE OF PB(BA, SR)2(LN, CE)2CU3OY (LN - LANTHANOID, Y=9-10.4), A NEW MEMBER OF THE PB SYSTEM

Pb(Ba, Sr)2(Ln, Ce)2Cu3O(y) (Ln: lanthanoid, y = 9.0-10.4) with (Pb, Cu) double layers and (Ln, Ce) fluorite layers was designed and obtained as a single phase. The structure of Pb(Ba, Sr)2(Ln, Ce)2Cu3O(y), which was derived from Pb(Ba, Sr)2YCu3O(y) by replacing oxygen-defect Y layers with (Ln, Ce)2O2 layers, was confirmed by high-resolution electron microscopy. The micro-structure of (Pb, Cu) double layers of a quenched specimen was examined by means of high-resolution image with an imaging plate. A slowly cooled specimen with an oxygen content of y = 10.2 lost 1.2 oxygen atoms above 580-degrees-C with an abrupt and reversible transition. The nature of this phase transition was similar to that of PbBaSrYCu3O(y) described in our previous paper. No superconductivity was found in Pb(Ba, Sr)2(Ln, Ce)2Cu3O(y) in spite of the CuO2 doublet sheets, similar to Pb2Sr2LnCeCu3O(y) with (Ln, Ce) fluorite layers.