Effects of SnO<SUB>2</SUB> Additives on the Bondability and Superconductivity of YBCO Superconductors

Abstract

The influence of tin oxide additives on the diffusion bondability and superconductivity of YBa 2 Cu 3 0 7-x ceramic was studied. The critical current density Jc and the critical temperature Tc were tested by the standard four-probe technique. In order to study the behavior and thermal properties of SnO 2 additives in the YBa 2 Cu 3 O 7-x superconductors in sintering processes, the phase structure of YBa 2 Cu 3 O 7-x powder with different amount of SnO 2 additives were investigated both by X-ray diffraction after sintering and by thermal analysis. The bonding strength of joints were measured by shearing test. The critical current density increased with the SnO 2 additives properly added. This improvement was considered as the results of such phenomena as follows: (1)The density of specimen increased with the SnO 2 additives increasing. (2) The pinning force to magnetic flux was became larger due to the existence of the additives. The shear strength of specimens increased with the SnO 2 additives increasing. It was feasible to bond the YBCO superconductors using the SnO 2 as the additive. The diffusion bonding thermal cycle would not affect the crystal structure of the YBCO.