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).

Journal Article · Sat Mar 01 04:00:00 EST 2003 · IEEE Trans. Appl. Supercond.

DOI:https://doi.org/10.1109/TASC.2003.809596· OSTI ID:961178

Maroni, V A; Murphy, N N; Mika, M; Luo, Z P; Tang, Y; Claus, H; Miller, D J; Park, J H; Dorris, S E; Fleshler, S; Williams, R K; Superconductor, American; ORNL,

We have investigated the possibility of forming a silver-sheathed 1212-type high-critical-temperature superconductor (HTS) with the same type of grain colony microstructure (GCM) that develops in the silver-sheathed Bi-2223 (Ag/Bi-2223) composite conductor. The basis for this study is that a silver-sheathed 1212-type superconductor having a GCM should exhibit (1) good long-length transport critical current properties, (2) better in-field performance than Ag/Bi-2223 due to the significantly shorter blocking layer distance in 1212-type as opposed to 2223-type HTS phases, and (3) long-length transport current capacity equaling or exceeding that of Ag/Bi-2223 in present-day applications. Three series of M{sub 1}Sr{sub 2}Y{sub 1-x}Ca{sub x}Cu{sub 2}O{sub z} (M-1212) compositions with M = (Bi,Pb), (Cd,Pb), and (Fe,Pb) were prepared in silver-sheathed/flat wire form by the powder-in-tube method. For M = (Bi,Pb), we were able to obtain over 80% conversion to a 1212-phase in a relatively short time (6 h) for oxygen partial pressures in the range from 0.08 to 0.21 atm and temperatures from 900{sup o}C to 940{sup o}C. The (Bi,Pb)-1212 phase grew with a GCM that had the same type of fiber texture found in Ag/Bi-2223 composites. However, within the range of processing conditions tolerated by a silver sheath, no transport critical current was achieved in any of the Ag/(Bi,Pb)-1212 specimens, including ones that showed the presence of an HTS phase. Various oxygen doping treatments performed at very high (ca. 88 atm O2), intermediate (1 atm O{sub 2}), and low oxygen partial pressures (0.01 atm O{sub 2}) failed to induce a global HTS phase that carried a transport current. The preponderance of evidence from these studies indicated that any superconductivity detected in Ag/(Bi,Pb)-1212 specimens was most likely due to trace amounts of either Bi-2201 or Bi-2212. For M = (Cd,Pb) and (Fe,Pb), M-1212 phases in appreciable quantity did form in the silver-sheathed composites after heat treatment, but those M-1212 phases had granular microstructures. In the case of Ag/(Cd,Pb)-1212, the superconductivity that was detected in several specimens appeared to originate from a 2212-like phase. In the case of Ag/(Fe,Pb)-1212, there was clear evidence for the formation of a superconducting 1212 phase, but neither the Ag/(Cd,Pb)-1212 nor the Ag/(Fe,Pb)-1212 specimens exhibited a measurable transport critical current, presumably (in the latter case at least) because of the absence of a GCM.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 961178
• Report Number(s): ANL/CMT/JA-45290
• Journal Information: IEEE Trans. Appl. Supercond., Journal Name: IEEE Trans. Appl. Supercond. Journal Issue: 1 ; Mar. 2003 Vol. 13
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

36 MATERIALS SCIENCE
BISMUTH COMPOUNDS
CADMIUM COMPOUNDS
CALCIUM COMPOUNDS
COATINGS
COMPARATIVE EVALUATIONS
COPPER COMPOUNDS
CRITICAL CURRENT
DEPLETION LAYER
FIBERS
HEAT TREATMENTS
HIGH-TC SUPERCONDUCTORS
IRON COMPOUNDS
LEAD COMPOUNDS
MICROSTRUCTURE
OXYGEN
PARTIAL PRESSURE
PERFORMANCE
PROCESSING
RANGE
SILVER
STRONTIUM COMPOUNDS
TEXTURE
TRACE AMOUNTS
TRANSPORT
YTTRIUM COMPOUNDS