Thin films, prepared by pulsed laser deposition and electron beam evaporation (EBE), were investigated by scanning electron microscopy before and after 200MeV 107Ag ion irradiation. The severe degradation of superconducting properties in irradiated pulsed-laser deposition film and the absence of the same in EBE film were correlated with the observed changes in their microstructures. The micrographs of the pulsed-laser deposited film exhibited an overall smoothing, flow pattern and reduction in size of the larger agglomerates after irradiation. On the other hand, the microstructure of the EBE film did not exhibit any significant change after irradiation. The flow pattern observed in the pulsed-laser deposition film could be understood on the basis of the viscoelastic model for irradiation-induced shear flow in amorphous solids. The observed degradation of the pulsed-laser deposition film could thus be attributed mainly to its disordered nature under irradiation, whereas the radiation hardness of the EBE film could be due to its higher crystallinity.

Study of Microstructural Changes in MgB2 Thin Film Superconductors Irradiated with 200MeV 107Ag Ions. H.Narayan, A.Gupta, A.V.Narlikar, K.N.Sood, R.Kishore, D.Kanjilal: Superconductor Science and Technology, 2004, 17, 1072-6