EXTRINSIC DEFECT IMPLANTATION IN SINTERED YBCO SLABS - MAGNETIC AND TRANSPORT-PROPERTIES

This paper deals with proton irradiation effects on the intragrain and intergrain magnetic and transport properties of sintered YBCO. We hav e irradiated slab-shaped samples with beams at different fluences and energies, aiming at checking the possibility to modify in a planned wa y critical currents by means of proton implantation. Magnetic characte rizations show enhanced intragrain pinning. Emphasis is given to the p ossibility to modulate intergrain magnetic properties by irradiation, determining critical current enhancement in optimal field and temperat ure ranges. Resistive measurements were performed in order to investig ate the complex transport phenomena in polycrystalline materials, wher e superconducting and normal conduction mechanisms coexist. Irradiatio n-induced effects on both superconducting and normal state resistivity are studied. The addition of extrinsic defects leads to enhanced tran sport properties, emerging especially when a magnetic field is applied .