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Title: Method of producing improved microstructure and properties for ceramic superconductors

A ceramic superconductor is produced by close control of oxygen partial pressure during sintering of the material. The resulting microstructure of YBa.sub.2 Cu.sub.3 O.sub.x indicates that sintering kinetics are enhanced at reduced p(O.sub.2). The density of specimens sintered at 910.degree. C. increased from 79 to 94% theoretical when p(O.sub.2) was decreased from 0.1 to 0.0001 MPa. The increase in density with decrease in p(O.sub.2) derives from enhanced sintering kinetics, due to increased defect concentration and decreased activation energy of the rate-controlling species undergoing diffusion. Sintering at 910.degree. C. resulted in a fine-grain microstructure, with an average grain size of approximately 4 .mu.m. Such a microstructure results in reduced microcracking, strengths as high as 191 MPa and high critical current density capacity.
Inventors:
 [1];  [2];  [3];  [4]
  1. (Naperville, IL)
  2. (Bloomington, IL)
  3. (Lombard, IL)
  4. (Glen Ellyn, IL)
Issue Date:
OSTI Identifier:
870456
Assignee:
University of Chicago (Chicago, IL) ANL
Patent Number(s):
US 5525586
Contract Number:
W-31109-ENG-38
Research Org:
Argonne National Laboratory (ANL), Argonne, IL
Country of Publication:
United States
Language:
English
Subject:
method; producing; improved; microstructure; properties; ceramic; superconductors; superconductor; produced; close; control; oxygen; partial; pressure; sintering; material; resulting; yba; cu; indicates; kinetics; enhanced; reduced; density; specimens; sintered; 910; degree; increased; 79; 94; theoretical; decreased; 0001; mpa; increase; decrease; derives; due; defect; concentration; activation; energy; rate-controlling; species; undergoing; diffusion; resulted; fine-grain; average; grain; size; approximately; results; microcracking; strengths; 191; critical; current; capacity; ceramic superconductor; average grain; oxygen partial; current density; grain size; partial pressure; critical current; activation energy; close control; ceramic superconductors; resulting microstructure; producing improved; ceramic superco; /505/

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