Higher electrical resistivity is observed in metals when dimensions approach the mean free path of the electrons. The effects of electron scattering at surfaces and at grain boundaries are then becoming substantial. This issue has been extensively studied on thin films but rarely on wires, where both small dimensions ͑width and height͒ influence the resistivity increase. In this study, copper wires having variable width and height down to 100 nm are investigated. An alternative approach is suggested in which the resistivity of such wires at different temperatures is compared to that of films having thickness that is equal to the height of the wires. The main outcome is a reliable model that overcomes the well-known difficulty of separating the contribution of surfaces to the resistivity from that of grain boundaries. It is shown that when both width and height of the wire are larger than one third of the mean free path, its resistivity exhibits a filmlike behavior with a separate contribution to the resistivity of each small dimension. The scattering of electrons at the surfaces of the investigated wires was best described by a zero specularity parameter, indicating the importance of this effect for the resistivity increase in small wires.

Materials with nanometric dimensions exhibit higher electrical resistivity due to additional scattering centers for the conduction electrons, mainly from surfaces and grain boundaries. In this study we focus on the effect of surfaces by implementing an experimental technique in which the resistivity of thin films is measured during and after etching them inside a solution. This technique enables to analyze the contribution of surfaces to the resistivity and gives a unique insight as for the effect of surface roughness. It is shown that the scattering of electrons from annealed copper films with smooth enough surfaces is mostly specular and that the resistivity in this case is dominated by the effect of grain boundaries. However, when the roughness of the surface becomes larger than the de Broglie wavelength of the electrons, a substantial increase in resistivity occurs. This roughness-induced resistivity is analyzed and shown to be much larger in certain cases than the resistivity predicted for a flat surface, even when all electron scatterings are assumed to be completely diffused.

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The dynamic response of alumina under shock compression was studied using planar impact experiments with different tile thicknesses. Stress-time measurements were made with manganin gauges backed by different backing materials in order to optimize gauge response. The results show an apparent decay in the Hugoniot elastic limit with propagation distance. However, further analysis reveals that this phenomenon is probably a measurement artifact, resulting from the relatively slow response times of manganin gauges.

The dependence of resistivity on temperature in thin metal films is investigated by extending the model of Mayadas and Shatzkes to include temperature dependence. It is shown that previous interpretations of a dominant grain boundary mechanism are not necessarily correct, and that the combined influence of grain boundaries and surfaces should be considered in the analysis of experimental results. The analytical expressions developed enable systematic studies of the different factors influencing the dependence of resistivity on temperature in thin metal films.