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Nanocrystalline Ag, Cu, and Ni thin films and their coarse grained counterparts are patterned using focused ion beam and then irradiated by Kr ions within an electron microscope at room temperature. Irradiation induced in-plane strain of the films is measured by tracking the location of nanosized holes. The magnitude of the strain in all specimens is linearly dose-dependent and the strain rates of nanocrystalline metals are significantly greater as compared to that of the coarse grained metals. Real-time microscopic observation suggests that substantial grain boundary migration and grain rotation are responsible for the significant in-plane strain. [ABSTRACT FROM AUTHOR]

Systematic experiments were performed by in situ observationofthe YBa2Cu3Oz(Y123or YBCO) melting. Remarkably, the superheating phenomenon was identifiedto exist in all commonly used YBCO thin films, that is, films depositedon MgO, LaAlO3(LAO), and SrTiO3(STO) substrates,suggesting a universal superheating mode of the YBCO film. Distinctively,YBCO/LAO films were found to possess the highest level of superheating,over 100 K, mainly attributed to the lattice match effect of LAO substrate,that is, its superior lattice fit with Y123 delaying the Y123 dissolvingand inferior lattice matching with Y2BaCuO5(Y211)delaying the Y211 nucleation. Moreover, strong dependence of the thermalstability on the substrate material for Y123 films was also foundto be associated with the substrate wettability by the liquid andthe potential element doping from the substrate. Most importantly,the understanding of the superheating behavior is widely valid formore film/substrate constructions that have the same nature as theYBCO film/substrate. [ABSTRACT FROM AUTHOR]