Document Type

Article

Publication Date

2-1-1992

Publication Title

Journal of Materials Research

Volume

7

Issue Number

2

First Page

283

Last Page

291

DOI

10.1557/JMR.1992.0283

Keywords

CO2, Y-Ba-Cu-O, Superconductors

Disciplines

Chemical Engineering

Abstract

The superconducting properties of YBa2Cu3O6+x reacted with various known ratios of O2/CO2 gas mixtures during sintering at different temperatures were studied. Jc was found to decrease drastically upon reaction with CO2, becoming zero at certain CO2 activities. The stability region for the 123 superconductor, as a function of CO2 activity and temperature, was empirically formulated as follows: log pCO2 < (−45,000)/T + 33.4. The grain boundaries in sintered samples with Jc = 0 were investigated with HRTEM in conjunction with EDS. Two distinct types of grain boundaries were observed. Approximately 10% of the grain boundaries were wet by a thin layer of a second phase, deduced to be BaCuO2. The remaining boundaries were sharp grain boundaries. The grain structure near the sharp grain boundaries was tetragonal. These two types of grain boundaries are thought to be responsible for Jc being zero.

Comments

Copyright © 1992 Materials Research Society. The definitive version is available online at http://dx.doi.org/10.1557/JMR.1992.0283.

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