Microstructural and electrical characterization of Joule heat welds in ultrathin Pt wires

This paper reports on the structural and electrical characteristics of Joule heat welds in ultrathin Pt wires with diameters of 600–800 nm. The wires have a bamboo structure where the crystal grains are aligned only in the axial direction. They were welded together in a self-completed manner in air by Joule heating. The electrical resistance of the welded wire system was measured using a potential drop technique. It was found by transmission electron microscope observations that the region affected by welding was very narrow and it appeared that a new grain boundary had been created in this region. Moreover, the welds were found to have good electrical characteristics and the electrical resistance at the weld depended on its cross-sectional area.