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Preparation, Thermal Processing Behavior And Characterization Of Powdered And Bulk Yba2Cu3O7−x From Freeze Dried Nitrate Solutions.

Published online by Cambridge University Press:  28 February 2011

N. Coppa ,
A. Bura ,
J. W. Schwegler ,
R. E. Salomon ,
G. H. Myer  and
J. E. Crow
N. Coppa
Affiliation:
Center for Materials Research, Temple University, Philadelphia, PA 19122
A. Bura
Affiliation:
Center for Materials Research and Technology, Florida State University, Tallahassee, FL 32306–3016
J. W. Schwegler
Affiliation:
Center for Materials Research, Temple University, Philadelphia, PA 19122
R. E. Salomon
Affiliation:
Center for Materials Research, Temple University, Philadelphia, PA 19122
G. H. Myer
Affiliation:
Center for Materials Research, Temple University, Philadelphia, PA 19122
J. E. Crow
Affiliation:
Center for Materials Research, Temple University, Philadelphia, PA 19122
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Abstract

Solutions of Y, Ba and Cu nitrate were spray-frozen. Very small particles consisting of atomic mixtures of these salts remained after the water was sublimed. These YBCO precursors were characterized and their behavior was studied in detail while they were thermally decomposed by a variety of techniques. Kilogram size batches are routine. The final YBCO products were obtained as powders and sintered bars. Sintered materials exhibited excellent phase purity (>99%) and super-conducting characteristics (Tc = 92 K), while powdered materials had secondary phases present. Some of these samples having high percentages of second phases exhibited sudden drops in resistivity to a few micro-ohms at 200 or 240 K followed by a zero resistance transition at 92 K. Coincident with this drop in resistance was a discontinuity in the magnetization.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 180: Symposium A – Better Ceramics Through Chemistry IV , 1990 , 935
Copyright
Copyright © Materials Research Society 1990

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References

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