NEW METHOD FOR MEASURING PINNING STRENGTH INSIDE GRAINS OF HTCS CERAMICS

We have designed a new setup and analysis route based on the Campbell' s method for measuring the critical current in superconductors. Our mo del takes consideration of the ceramics granular nature, the existence of intergrain and intragrain currents. We obtain the variation of the pinning strength P-v as a function of p(g), which is the radial posit ion inside an average grain. We apply this scheme to Bi1.7Pb0.3Sr2Ca2C u3O10-y ceramics synthesized by a vitreous route. The intragrain criti cal current is 10(5) A/cm(2) at 40K with zero DC magnetic field. Some important increase of the pinning strength is observed near the grain surface.