GRAIN-BOUNDARY DIFFUSION IN BI-PB-SR-CA-CU-O COMPOUND

Zinc has been diffused along the grain boundaries of Bi 1.5Pb0.5Sr2Ca2Cu3O 10 compound at relatively low temperatures. For diffusion at 260 degrees C for 150 hours, the transition temperature, Tc, at zero resistance dropped from 105 to 92 K, while the transport critical current density, Jc, dropped from 12.5 to 4.2 A cm-2. The normal state resistivity at room temperature increased from 3.7 to 7.0 m Omega cm. The presence of Zn was confirmed by Auger electron microscopy. Diffusion of Zn at 450 degrees C for 150 hours deteriorated the superconducting materials further. Tc dropped to 83 K and Jc to 3.4 A cm-2. The results show that Tc and Jc in high-Tc superconductors can be affected by selected doping of the grain boundaries.