Magnetic susceptibility and critical currents of (Tl0.5Pb0.5) Sr2(Ca0.9Gd0.1)Cu2Oy superconductor

The (Tl0.5Pb0.5)Sr2(Ca0.9Gd0.1)Cu2Oy superconductor has been fabricated by the wet chemical gel technique. The structure of the superconductor was determined as a Tl-1212 tetragonal structure by X-ray diffraction technique. Magnetic properties of the specimen were characterized by measurements of the real and imaginary parts of ac susceptibility in function of the temperature and of the ac applied magnetic field. The peaks of imaginary part of ac susceptibility shifted to lower temperatures upon increasing magnetic field. Taking advantage of the Bean model, the critical current densities of the samples were calculated. The temperature dependences of the critical current were successfully fitted using the powerlaw from thermally activated magnetic flux creep model.