Effect of silver addition to the bismuth-lead-strontium-calcium-copper-oxygen superconductor: Enhancement in critical current density

Resistivity, XRD and a.c. susceptibility measurements have been carried out to study the effect of silver addition (0-50 wt%) to a Bi1.6Pb0.4Sr2Ca2.2 Cu3.5Oy composition prepared by two different techniques, namely, the usual solid state reaction technique and a solution technique. The specimens prepared by solid state technique show a degradation in Tc, as well as J c (the critical current density computed from the granular model of Clem) with the increase in silver concentration from 0 to 50 wt%. on the other hand, specimens prepared by the solution technique, which yields a material with strong intergrain links, show a systematic improvement in J c (except for 5wt% silver addition) right up to 50 wt%. The widely different results on silver addition to the Bi-system of the high-Tc superconductors as reported by different authors can thus be attributed to the strength of the intergrain coupling which in turn will depend on preparation technique