Synthesis of the Ba-substituted Bi-2212 phase of BiPb(Sr,Ba) 2 RE Cu 2 O 8

We have attempted to synthesize the Bi-2212 phase of BiPbSr2−x Bax RECu2O8+δ (RE = Nd, Sm, Gd, Y, Yb) by the conventional solid-state reaction method. The completely Ba-substituted sample with x = 1 has been successfully synthesized only for Nd. As the ionic radius of RE decreases, the solubility limit of Ba decreases. It has been found that the substitution of Ba for Sr requires the expansion of both the Bi–O and RE layers as well as the synthesis in a reducing atmosphere to suppress the formation of BaBiO3-related phases. Unfortunately, the hole-doping to semiconducting BaPbBa2NdCu2O8+δ has not been successful.