Magnetic Properties of Te-Doped Bi-Pb-Sr-Ca-Cu Superconductors

The magnetic properties of Te-doped Bi1.4Pb0.6Sr2Ca2Cu3TexOy superconductors were studied. Samples with x= 0.05 to 0.2, fired at 850°C for 50 hours in air, showed zero resistance above 100K. The volume fraction of the superconducting phases was increased by Te doping, and was maximum at x=0.1. On measuring hysteresis loops at 77K, the residual magnetization for the sample with x= 0.1 was found to be much larger than that for x=0. The critical current density for Te-doped samples was improved under high magnetic fields. These results suggest that Te doping is effective for increasing the pinning force. WDX analysis indicated that high-Tc phases contained 0.6 at% Te.