Harmonic analysis of AC magnetic susceptibility of YBCO/Ag produced by chemical amorphous citrate route

The dependence of AC magnetic susceptibility on temperature and magnetic fi eld amplitude of YBCO/Ag superconductors produced by a modified citrate rou te is studied. Superconducting powders have been prepared with nine differe nt heat treatments, sintered and characterized structurally and magneticall y. X-rays analysis, scanning electron microscopy and scanning Auger microsc opy show the compositional purity and homogeneity. the size of the grains, and the way silver is dispersed in the sample. AC susceptibility is interpr eted in terms of a critical-state model providing a quantitative estimate o f the critical current density and qualitative insight on the flux dynamic inside the samples. (C) 2001 Elsevier Science B.V. All rights reserved.