New superconducting Pb-based 1212 cuprates containing boron, (Pb0.5B0.5)(Sr2−xBax)(Y1−yCay)Cu2Oz

New superconducting layered cuprates of the 1212 phase have been synthesized in the (Pb0.5B0.5)(Sr2−xBax)(Y1−yCay)Cu2Oz system. X-ray diffraction study shows that the almost-single phase samples are obtained within a region of 0 ⩽ x ⩽ 0.6 and 0 ⩽ y ⩽ 0.6. Then, the sample with x = 0.5 and y = 0.6 among them is found to have the maximum superconducting transition temperature of about 45 K. The crystal structure of this sample has a tetragonal symmetry with the lattice parameters of a = 0.3826 nm and c = 1.195 nm.