Abstract
New cuprates with nominal composition (Pb0.8W0.2)Sr2(Nd1 − xCax)Cu2O7 − δ(0≤x≤1) were synthesized by solid-state reaction in N2. The crystal structure was characterized by X-ray powder diffraction (XRD) as tetragonal. Direct current electrical resistance measurements were applied to check the existence of superconductivity in these cuprates. Superconductivity with Tc (onset) up to 82 K is observed when x = 0.6. Synthesis in N2 is necessary in obtaining superconductivity in these cuprates. Preparation in air or post-treatment in flowing oxygen destroys superconductivity. A comparison is made with previous Pb-based 1212 superconducting oxides. The valence of Pb and the possible position of W in the lattice are discussed.
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