Abstract
Ca-free (Pb/Cu)-3212 phase in a Pb-Sr-Yb-Cu-O system has been studied. Almost-single phase samples were synthesized at a nominal composition of (Pb2.1Cu)Sr2(Yb1-xSrx)Cu2Oy(0.0≤x≤0.3) by annealing in nitrogen. The sample at x=0.3 exhibited superconductivity with Tc(onset)=65K, Tc (zero resistivity)=17K. The powder X-ray diffraction pattern for x=0.3 sample could be indexed with orthorhombic symmetry of a=5.384Å, b=5.424Å and c=15.764Å. Thermogravimetric analysis and annealing treatments at various temperatures in nitrogen suggested that the crystallizing temperature for the (Pb/Cu)-3212 sample at x=0.3 was estimated to be 720°C.
