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Preliminary Investigation of Processing and Phase Diagram Construction in the Y‐Sr‐Cu‐O System

Published online by Cambridge University Press:  28 February 2011

T. D. Rolin
Affiliation:
University of Alabama in Huntsville, Departments of Chemistry
F. S. Cheng
Affiliation:
Physics, Huntsville, AL 35899.
J. R. Ashburn
Affiliation:
Physics, Huntsville, AL 35899.
H. Y. Cheng
Affiliation:
Physics, Huntsville, AL 35899.
E. E. Anderson
Affiliation:
University of Alabama in Huntsville, Departments of Chemistry
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Abstract

We have investigated the Y‐Sr‐Cu‐O system which has been reported to form a K2NiF4‐type superconducting phase (TC∼40K) and a “123”‐type phase (Tc‐80K). Difficulties in preparing single phase materials by standard solid state reaction of carbonates and oxides have compelled us to explore other methods. A two‐stage solid state processing technique in addition to a coprecipitation method will be discussed along with the relative advantages and disadvantages of each. Using data obtained from XRD and EDS, we have mapped some of the YO1.5‐SrO‐CuO ternary phase diagram in anticipation of continued efforts at single crystal growth.

Type
Research Article
Copyright
Copyright © Materials Research Society 1990

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References

1 Wu, M.K., Ashburn, J.R., Higgins, C., Loo, B.H., Burns, D.H., Ibrahim, A., Rolin, T.D., Chien, F.Z., and Huang, C.Y., Phys. Rev. B37, 9765 (1988).Google Scholar
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4 Neither can we rule out the possiblity of a crucible‐contaminated aluminum‐stabilized YSr2Cu1‐x Alx)O7‐y Phase superconducting for sufficiently low values of x. We have found the “123” structure to be stable for decreasing values of x (at least as low as 0.08) when processed at increasing temperatures (as high as 1060°C). Very recently, crystals of yet‐to‐be‐determined composition but “123‐like” morphology have been found in “123” melts, but only adjacent to alumina surfaces, whereas attempts with yttria‐stabilized zirconia containers have failed repeatedly. This also suggests the possibility that the pure 123 phase may be stabilized by elevated oxygen pressures (> 1 atm).+1+atm).>Google Scholar