Phase transformations in melt-spun Y-Ba-Cu-O bulk superconductor
Conference
·
OSTI ID:42824
Powders of YBa{sub 2}Cu{sub 3}O{sub 7} (Y123) and compositions around Y123 were heated by a containerless process and melt-spun in 21% oxygen atmosphere at temperatures of 1400 to 1650 C. Homogeneous materials were obtained with micron and submicron crystalline phases uniformly dispersed in an amorphous matrix. For Y123, the crystalline phases are identified by XRD as BaCu{sub 2}O{sub 2} and Y{sub 2}O{sub 3} when the melt-spinning temperature is below 1600 C. At 1650 C, the crystalline phases are Y{sub 4}Ba{sub 3}O{sub 9}, BaCu{sub 2}O{sub 2} and Y{sub 2}O{sub 3}. The phase composition of the solidified melt is directly related to the oxygen content of the melt and can be related to the equilibrium phase diagrams at lower oxygen partial pressures. Isothermal annealing is oxygen at temperatures 500 to 950 C reveals that the crystallization sequence is: Y123 begins to form at 500 C, Y123 with minor amount of Y{sub 2}BaCuO{sub 5} at 800 C, Y123 with very minor amount of CuO at 900 C, and single phase Y123 at 950 C.
- Research Organization:
- Ames Lab., IA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 42824
- Report Number(s):
- IS-M--814; CONF-941013--34; ON: DE95010237
- Country of Publication:
- United States
- Language:
- English
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