Critical currents, Magnetization and Microwave Absorption of (Tl0.5Pb0.5)Sr2(Ca0.8Gd0.2)Cu2Oz Superconductor

The bulk (Tl0.5Pb0.5)Sr2(Ca1-xGdx)Cu2Oz superconductors with x = 0:1, 0.2 and 0.3 have unique and very interesting magnetic and electrical properties. In this paper we focused our attention on the superconductor with gadolinium content x = 0.2. We measured the magnetic field dependences of the transport critical currents, the microwave absorption as well as the magnetization for different temperatures. The critical temperature of this sample is Tc = 105.3 +- 0:2 K and the transition width DeltaT90%-10% = 3.6 +- 0.2 K. The critical current of this superconductor is Jc = 1820 +- 10 A/cm2 at 77 K. The data were analyzed within the frame of the Bean and Kim models as well as the percolation model.