Synthesis and superconductivity of new layered oxides (Pb_2-xSb_x)Sr₂(Y_1-yCa_y)Cu₃O₈

Abstract

New layered cuprates with nominal composition (Pb2-xSbx)Sr2(Y1-yCay)Cu3O8 were synthesized by solid-state reaction in N2. These samples were characterized by x-ray powder diffraction and dc electrical resistivity measurements. Nearly single 3212 phase samples were obtained in the range 0<x0.5 and 0 y0.5. The introduction of Sb into the Pb sites brought about slight drops of resistivity at 61 K, 48 K and 61 K in the x = 0.1, 0.2 and 0.3 samples, respectively. Superconductivity with Tconset up to 69 K was found in the range 0.1 x0.3 after Ca was doped into the Y sites.