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Title: Method of manufacture of single phase ceramic superconductors

Abstract

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}) and that because of second phase precipitates, grain growth is prevented. The density of specimens sintered at 910 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 C resulted in a fine-grain microstructure, with an average grain size of about 4 {mu}m. Post sintering annealing in a region of stability for the desired phase converts the second phases and limits grain growth. The method of pinning grain boundaries by small scale decompositive products and then annealing to convert its product to the desired phase can be used for other complex asides. Such a microstructure results in reduced microcracking, strengths as high as 230 MPa and high critical current density capacity. 25 figures.

Inventors:
; ; ;
Publication Date:
Research Org.:
Univ. of Chicago, IL (United States)
OSTI Identifier:
35077
Patent Number(s):
US 5,401,712/A/
Application Number:
PAN: 7-947,324
Assignee:
Univ. of Chicago, IL (United States)
DOE Contract Number:  
W-31109-ENG-38
Resource Type:
Patent
Resource Relation:
Other Information: PBD: 28 Mar 1995
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; HIGH-TC SUPERCONDUCTORS; SINTERING; MICROSTRUCTURE; YTTRIUM OXIDES; BARIUM OXIDES; COPPER OXIDES; CONTROLLED ATMOSPHERES

Citation Formats

Singh, J P, Poeppel, R B, Goretta, K C, and Chen, N. Method of manufacture of single phase ceramic superconductors. United States: N. p., 1995. Web.
Singh, J P, Poeppel, R B, Goretta, K C, & Chen, N. Method of manufacture of single phase ceramic superconductors. United States.
Singh, J P, Poeppel, R B, Goretta, K C, and Chen, N. Tue . "Method of manufacture of single phase ceramic superconductors". United States.
@article{osti_35077,
title = {Method of manufacture of single phase ceramic superconductors},
author = {Singh, J P and Poeppel, R B and Goretta, K C and Chen, N},
abstractNote = {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}) and that because of second phase precipitates, grain growth is prevented. The density of specimens sintered at 910 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 C resulted in a fine-grain microstructure, with an average grain size of about 4 {mu}m. Post sintering annealing in a region of stability for the desired phase converts the second phases and limits grain growth. The method of pinning grain boundaries by small scale decompositive products and then annealing to convert its product to the desired phase can be used for other complex asides. Such a microstructure results in reduced microcracking, strengths as high as 230 MPa and high critical current density capacity. 25 figures.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1995},
month = {3}
}