XIONG Xiaotao, LI Yang, MA Qingzhu, CAO Guohui
(Department of Materials Physics, University of Sicence and Technology)
Abstract: Investigation on the effect of Sn/Pb - clopped Bi-2212 superconductors has been carried out by the X — ray diffraction, together with simultaneous measurements of the spectra of positron annihilation lifetime and positron Doppler broadening. The results of samples with different dopping level show that the occupation of Sn atoms on Bi sites. At weak dopping level, Sn clopping results in a enhancement of cooperation between layers and increment of superconducting transition temperature. At the strong dopping level, Sn atoms occupy the sites of Cu-O layers, and at the same time, the other nonsuperconducting phases appear, which results in a decline of the superconducting transition temperature.
Keywords: X - ray diffraction, Bi -2212 phase, Sn/Pb clopping, Superconductors