Improvement of superconducting (Hg,Re)-1223 ceramics synthesised by the sealed quartz tube technique

We analyse the effect of several synthesis conditions and parameters on the superconducting properties of (Hg,Re)-1223 ceramics obtained by the sealed quartz tube technique. The incorporation of liquid mercury results in an i ncrease of the superconducting volume fraction, probably as a consequence o f the displacement of the reaction towards the superconducting phase format ion. On the other hand, the oxygen content of the precursor is shown to hav e a significant effect on the sample compactness, and therefore on the inte rgrain connectivity of the superconductor. Finally, wrapping the unreacted superconductor pellet in a gold foil has also beneficial effects on the qua lity of the synthesised samples. (C) 1999 Elsevier Science B.V. All rights reserved.