Title :
Effects of heating temperature and atmosphere on critical current density of Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/Ag/sub 0.8/O/sub y/ Ag-sheathed tapes
Author :
Endo, A. ; Nishikida, S.
Author_Institution :
Sumitomo Metal Ind. Ltd., Amagasaki, Japan
fDate :
3/1/1993 12:00:00 AM
Abstract :
In partial melt processing of Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/Ag/sub 0.8/O/sub y/ silver sheathed tapes, the effects of heating temperature and atmosphere on the critical current density, J/sub c/, were studied. It was found that J/sub c/ is higher for the samples treated in pure oxygen than those in air and has the maximum value at a heating temperature of 885 degrees C. During partial melting, nonsuperconducting Sr-Ca-Cu-O precipitates grew in size with increasing temperature and caused a decrease of J/sub c/. The composition of the Sr-Ca-Cu-O phases in the tapes treated at 885 degrees C was (Sr,Ca)/sub 1/Cu/sub 1/O/sub y/ in air and (Sr,Ca)/sub 3/Cu/sub 5/O/sub y/ in oxygen. The size of precipitates in oxygen was smaller than in air. The highest J/sub c/ value, 1.2*10/sup 5/ A/cm/sup 2/ at 8 T and 4.2 K, was achieved in oxygen.<>
Keywords :
bismuth compounds; calcium compounds; composite superconductors; critical current density (superconductivity); heat treatment; high-temperature superconductors; melting; precipitation; silver; stoichiometry; strontium compounds; superconductive tunnelling; 4.2 K; 8 T; 885 degC; Bi/sub 2/Sr/sub 2/CaCu/sub 2/Ag/sub 0.8/O/sub y/-Ag; composition; critical current density; heating temperature; high temperature superconductivity; melt processing; precipitates; sheathed tapes; Atmosphere; Bismuth; Critical current; Critical current density; Heating; Magnetic field measurement; Powders; Strontium; Temperature dependence; Wires;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
