Irradiation-induced inter- and intra-granular modifications by 120 MeV S ions in YBa2Cu3O7 thick films

The evolution of microstructure under swift heavy ion (SHI) irradiation is probed in a granular medium such as YBCO thick films prepared through diffusion reaction technique. From the temperature-dependent in situ resistivity measurement during ion irradiation, we have been able to isolate the irradiation induced modifications at the grain boundaries and the grains. With 120 MeV S ion irradiation, we show that in addition to damaging the insulating grain boundaries and hence destroying superconducting phase coherence, ion irradiation brings about an improvement in the microstructure of the cuprates. Irradiation is shown to induce alignment of the grains in an otherwise randomly oriented granular superconductor.