Magnetic Field Dependence of the Transport Critical Current Density in the Superconductor Family ReBa2Cu3O7-x

The magnetic field dependence of the transport critical current density has been investigated at temperatures of 78K and 68K in bulk polycrystalline samples of the hightemperature superconductor ReBa2Cu3O7-x, where Re (rare earth) = Y (yttrium), Er (erbium), Yb (ytterbium), Ho (holmium), and Dy (dysprosium). Samples were sintered in 1⁄4 inch pellet form after the conventional ceramic processing techniques, and mechanical pressure contacts were used for these four-probe measurements. A 1.4 – Tesla magnet was used to provide the magnetic field, and a 500W current supply was used to provide steady currents as high as 1A. Onset critical temperatures for these samples were measured as Y (90K), Er (89K), Yb (89K), Ho (88K), and Dy (89K), the transport critical current density increases as we cool them from 78K to 68K.