Lanthanum doping of YBa₂Cu₃O_x

A wide variety of cation substitutions have been tried in the 1-2-3 compound, YBa₂Cu₃O_x, in the hope that its superconducting properties can be improved. While significant improvement has not been achieved, the response of the material to such substitutions can still be helpful in understanding its defect chemistry. In this paper, we report on measurements of the equilibrium oxygen content, by thermogravimetry, and the electrical conductivity of YBa_2−zLa_zCu₃O_x, with z = 0, 0.1, and 0.2. The results are consistent with the view that the stoichiometric composition for this system, YBa₂Cu₃O₆, is a highly acceptor-doped material.