Title :
Effects of carbon additions to melt-processed YBa/sub 2/Cu/sub 3/O/sub x/ and Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/ compacts
Author :
Sengupta, S. ; Todt, V.R. ; Goretta, K.C. ; Miller, D.J. ; Chen, Y.L. ; Balachandran, U.
Author_Institution :
Supercond. Components Inc., Columbus, OH, USA
fDate :
6/1/1997 12:00:00 AM
Abstract :
YBa/sub 2/Cu/sub 3/O/sub x/ (Y-123) and Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/ (Bi-2212) compacts were partial-melt processed. Carbon was introduced into the compacts either by vibratory milling in an organic solution or by heat treating in an atmosphere containing a controlled concentration of CO/sub 2/. The presence of carbon had a strong effect on the melting response of Y-123, but not Bi-2212. For both materials, magnetic-hysteresis width was strongly expanded with added carbon. Transmission electron microscopy revealed nanometer-scale precipitates in specimens exposed to excess carbon. These precipitates are thought to be responsible for enhanced flux pinning.
Keywords :
barium compounds; bismuth compounds; calcium compounds; carbon; ceramics; flux pinning; heat treatment; high-temperature superconductors; magnetic hysteresis; melting; nanostructured materials; powder technology; precipitation; strontium compounds; transmission electron microscopy; yttrium compounds; Bi-2212; Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/ compacts; Bi/sub 2/Sr/sub 2/CaCu/sub 2/O:C; CO/sub 2/; Y-123; YBa/sub 2/Cu/sub 3/O:C; carbon additions; enhanced flux pinning; heat treating; magnetic-hysteresis width; melt-processed YBa/sub 2/Cu/sub 3/O/sub x/; melting response; nanometer-scale precipitates; organic solution; partial-melt process; precipitates; transmission electron microscopy; vibratory milling; Atmosphere; Bismuth; Flux pinning; Magnetic flux; Magnetic materials; Milling; Organic materials; Strontium; Temperature control; Transmission electron microscopy;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
