Title :
Study of the effect of the Sr/Ca ratio on the microstructure and critical current density of BSCCO 2212 Ag-sheathed tapes
Author :
Zhang, W. ; Pupysheva, O.V. ; Ma, Y. ; Polak, M. ; Hellstrom, E.E. ; Larbalestier, D.C.
Author_Institution :
Appl. Supercond. Center, Wisconsin Univ., Madison, WI, USA
fDate :
6/1/1997 12:00:00 AM
Abstract :
The effect of the Sr/Ca ratio and Bi content on the microstructure and J/sub c/ of Ag-sheathed 2212 tapes was studied. Changing the Sr/Ca ratio changed the melting temperature of 2212 phase, the phase assemblage in the melt, and the nonsuperconducting phases in the fully processed tape. In tapes with Sr/Ca=2.75, the 2201 phase crystallizes from the melt before 2212 during cooling, and this 2201 remains in the microstructure. In tapes with Sr/Ca=1.3, there is more liquid left after cooling, and it converts to 2201 as the tape cools to room temperature. Fully processed tape with overall composition 2.1:2:1:2 had the most homogeneous microstructure and highest J/sub c/.
Keywords :
bismuth compounds; calcium compounds; critical current density (superconductivity); crystal growth from melt; crystal microstructure; high-temperature superconductors; silver; strontium compounds; BSCCO 2212 Ag-sheathed tapes; Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8/-Ag; Sr/Ca ratio; critical current density; high temperature superconductor; melt; microstructure; phase assemblage; Bismuth compounds; Cooling; Critical current density; Crystal microstructure; Crystallization; Heat treatment; Powders; Strontium; Superconducting coils; Temperature;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
