Improved critical current of superconducting Bi2223 - Ag tapes for current lead application by addition of `large' silver particles

Abstract

The effect of silver additions on the microstructure and superconducting properties of (Bi, Pb) 2 Sr 2 Ca 2 Cu 3 O x (Bi2223)-Ag tapes has been investigated. We find a strong dependence on both the silver content and especially the silver particle size. The addition of small (5 µm) particles results in a slight reduction of the critical current. Large (400 µm) particles are squeezed into long flat layers, leading to better grain alignment, grain density and phase purity of the 2223 phase along these layers. As a consequence, the critical current is increased by up to 60% in self-magnetic field, and even more in an external magnetic field.

Introduction of pinning centres into Bi - (Pb) - Sr - Ca - Cu - O superconductors

“…It should be pointed out that the reproducibility of the PFDR process is rather poor owing to the difficulty of controlling the melt step. Recently, a new process was developed by the principal author's group which can achieve the same phase assemblage as achieved by the PFDR process but with good reproducibility [122]. Figure 22 shows the phase assemblage of the tape fabricated from the normal process (A) which contains nearly pure 2223 with undetectable amounts of Bi-2212 remaining.…”

“…Recently, a similar result on J c enhancement was also observed by applying a slow cooling process at the end of heat treatment. During the slow cooling process the Bi-2223 phase was partially decomposed into Bi-2212 and Pb-rich phase which act as pinning sites as shown by the improvement in J c and IL [122].…”

Bi‐based superconductors with nanosized silver dopant

“…Not only the amount of Ag mixed into the composite but also the size of Ag particles is one of the most important factors for the microstructure and the superconducting properties. The various results for composites with 0.5-30 wt% Ag and Ag-particles size from 3 µm-2 mm have been presented [5,[8][9][10]. Critical current density is sensitive to the presence of a magnetic field.…”