Effect of Ag/Ag₂O additions on the resistive behavior of preformed YBa₂Cu₃O_7-δ compacts in the low temperature sintering regime

Contacts between the individual ceramic particles dictate the resistive behavior of bulk, polycrystalline, preformed YBa₂Cu₃O_7-δ compacts in the low temperature sintering regime. Ag/Ag₂O 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/Ag₂O results in enhanced resistive properties due to improved interparticle contacts. The thermal decomposition of Ag₂O in the presence of 123 is unaltered, as shown by DTA and TGA analysis. Hence, the presence of Ag₂O at temperatures higher than its normal decomposition temperature appears unlikely. For sintering temperatures below 600°C, internal oxidation due to dissociation of Ag₂O 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 Ag₂O additions and the benefit of oxygen donation by Ag₂O appears to be small. The addition of Ag/Ag₂O and the use of high compaction pressures, reduce the minimum sintering temperature to attain macroscopic zero resistivity from 900-950°C to ∼ 800°C.