The electrical and magnetic properties of the (Bi1 − yCdy)Sr2(Y1 − xCax)Cu2O7 − δ series

(Bi0.33Cd0.67)Sr2YCu2O7 − δ can be synthesized single phase by XRD, between 800 and 950 °C. It has a tetragonal structure, space group P4mmm, and lattice parameters a = 3.802 Å and c = 11.96 Å. The Cd site can be fully replaced with an appropriate MII ion and the Y site can be chemically substituted up to 100% by lanthanide ions with ionic radii falling between those of Nd and Gd, with a measurable shift in a and c axis lattice parameters. As synthesized, (Bi0.33Cd0.67)Sr2YCu2O7 − δ is semiconducting and paramagnetic down to 4 K. Superconductivity can be induced by a post-synthesis annealing in high pressure oxygen to give Tc = 40 K. Thermopower measurements show that the material is underdoped with S290k = 50 μVK−1. Introduction of extra charge carriers to raise Tc by doping Ca on the Y site is not chemically possible with the synthesis techniques used.