Tetragonal-to-Orthorhombic Transition and Disappearance of Superconductivity in the Pb-Doped Bi2Sr2CuOy System

Abstract
A series of superconductors Bi2.1-x Pb x Sr1.9CuO y with 0.05≤x≤0.5 were synthesized in polycrystalline form. Tetragonal to orthorhombic transition was found at around x=0.1. By the introduction of Pb, it was found that the average valence of Cu increases, whereas the superconducting transition temperature decreases. The system becomes more metallic with increasing x.