The structural analysis of a superconducting (Pb/Cu)-1222 phase, (Pb0.5Cu0.5)(Sr0.875Eu0.125)2(Eu0.75Ce0.25)2Cu2 Oz (z≈9), is performed by Rietveld analysis using X-ray powder diffraction data. Pb, Cu and O atoms constituting the (Pb/Cu)O monolayer in this crystal are found to be displaced from their ideal crystallographic sites as previously reported for the (Pb/Cu)-1212 compound. In addition, (Pb, Cu)-1222 compounds with nominal compositions of (Pb, Cu)(Sr, R)2(R', Ce)2Cu2Oz (R, R': rare-earth element) are synthesized and characterized. Nearly single-phase samples are successfully obtained for the compounds with R = R′ = Pr, Sm, Eu, Gd, Dy, Y or Ho, and for those with a pair of rare-earth elements, (R, R′) = (La, Eu), (Nd, Eu), (Nd, Dy), (Nd, Y), (Nd, Er), (Sm, Eu) or (Eu, Gd). Superconductivity is observed for the samples with R = R′ = Sm, Eu or Gd and also for those with (R, R′) = (La, Eu), (Nd, Eu), (Sm, Eu) or (Eu, Gd).
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