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Effect of Ag/Ag2O additions on the resistive behavior of preformed YBa2Cu3O7−δ compacts in the low temperature sintering regime

1990; Elsevier BV; Volume: 168; Issue: 3-4 Linguagem: Inglês

10.1016/0921-4534(90)90535-m

1873-2143

A. Goyal, S. J. Burns, Paul D. Funkenbusch,

Superconductivity in MgB2 and Alloys

Abstract Contacts between the individual ceramic particles dictate the resistive behavior of bulk, polycrystalline, preformed YBa 2 Cu 3 O 7−δ compacts in the low temperature sintering regime. Ag/Ag 2 O additions to performed 123 are investigated, with an aim to lower the sintering temperature required to achieve macroscopic zero resistivity in particulate cermet superconductors. The addition of Ag/Ag 2 O results in enhanced resistive properties due to improved interparticle contacts. The thermal decomposition of Ag 2 O in the presence of 123 is unaltered, as shown by DTA and TGA analysis. Hence, the presence of Ag 2 O at temperatures higher than its normal decomposition temperature appears unlikely. For sintering temperatures below 600°C, internal oxidation due to dissociation of Ag 2 O may serve as an efficient mechanism for oxygenating the 123 phase. However, for sintering temperatures close to 800°C, Ag additions are as effective as Ag 2 O additions and the benefit of oxygen donation by Ag 2 O appears to be small. The addition of Ag/Ag 2 O and the use of high compaction pressures, reduce the minimum sintering temperature to attain macroscopic zero resistivity from 900–950°C to ∼ 800°C.