Intergranular critical current density in polycrystalline (Bi-Pb)-2223 high temperature superconductor by ac susceptibility measurements

The field dependence of real (chi') and imaginary (chi') component of ac susceptibility of superconductors within the critical state model can conveniently be used for evaluating the critical current when field amplitude is larger than the penetration field. A method to analyze the real (chi') and imaginary (chi') component of fundamental ac susceptibility with the objective of extracting the temperature dependence of critical current density J(c)(T) is reported. The procedure makes use of the ac susceptibility data of two polycrystalline (Bi-Pb)-2223 samples measured with different excitation amplitudes below and close to the critical temperature. The temperature dependence of J(c) is extracted using the isothermal scan over chi' and chi' data. Results obtained from this procedure are found to be in fair agreement with J(c)(T) calculated from traditional "loss-maximum" data.