Superconductivity in New Pb-Based 1222 Layered Cuprates of (Pb0.75W0.25)Sr2(Eu2.0−xCex)Cu2Oz

New Pb-based 1212 cuprates of (Pb0.8W0.2)Sr2(Nd1−x Ca x )Cu2O7−δ were synthesized. The sample with x=0.6 was reported to show superconductivity with an onset temperature up to 82 K. Interestingly, in order to obtain superconductivity of the sample, synthesis in N2 was necessary, then synthesis in air or post-treatment in O2 led to the disappearance of superconductivity.