Phase stability and grain growth in an Ag/Bi-2223 composite conductor prepared using fine-grained Bi-2223 as a precursor.
We have investigated the stability and microstructural transformability of the Bi-2223 phase in a silver-sheathed monofilament composite tape fabricated using fine-grained Bi{sub 1.7}Pb{sub 0.3}Sr{sub 1.9}Ca{sub 2.0}-Cu{sub 3.0}O{sub y} (Bi-2223) as the precursor powder. The fully formed Bi-2223 precursor was prepared using established procedures. The purpose of this study was to explore the prospects for growing textured, large-grain-size Bi-2223 from the fine-grained precursor by process parameter perturbations. These perturbations included thermal ramp up variations, programmed heat treatment temperature and oxygen pressure fluctuations, and parameter manipulations during cool-down. Our results show that the types of heat treatments used in conventional oxide-powder-in-tube (OPIT) processing do not facilitate Bi-2223 grain growth when the precursor powder is preconcerted Bi-2223. We also observed that the Bi-2223 partially. decomposed during conventional thermal ramp-up in 0.075 atm O{sub 2}, but that this decomposition can be inhibited by ramping up in a reduced oxygen pressure. A pathway was found for back-reacting the fine-grained Bi-2223 (to Bi-2212, Bi-2201 and nonsuperconducting secondary phases), then reforming large-grained Bi-2223 in a colony microstructure having some distinct differences from that produced during conventional OPIT processing.
- Research Organization:
- Argonne National Lab., IL (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 10737
- Report Number(s):
- ANL/CMT/CP-96121; TRN: AH200127%%306
- Resource Relation:
- Conference: 1998 Applied Superconductivity Conference, Palm Desert, CA (US), 09/13/1998--09/18/1998; Other Information: PBD: 17 Sep 1998
- Country of Publication:
- United States
- Language:
- English
Similar Records
Search for a silver-sheathed 1212-type superconductor with a grain colony microstructure : M{sub 1}Sr{sub 2}Y{sub 1-x}Ca{sub x}Cu{sub 2}O{sub z} with M = (Bi,Pb), (Cd,Pb), and (Fe,Pb).
Improved Bi-2212/Ag performance as a competitor to Bi-2223/Ag in high-T{sub c} superconductor wire applications