Structure, conductance and strength of iridium wires of single atom width

The formation of iridium (It) wires of single-atom width during the contact and subsequent retraction of two nanometer-sized Ir tips was observed by in situ transmission electron microscopy with simultaneous measurements of conductance and force. The Ir wires, composed of a few atoms, grew straight along the retraction direction with an interatomic distance of 0.21-0.30 nm. The mechanical properties, i.e., elastic limit, Young's modulus and strength, of individual Ir wires were analyzed on the basis of the mechanics of materials on an atomic scale. It was found that in contrast to coarse-grained Ir crystals, the strength and elastic limit of the single-atom-width Ir wires increased to 25 +/- 17 GPa and 0.21 +/- 0.04, respectively, while Young's modulus decreased to 90 55 GPa. The conductance of the Ir wires at room temperature ranged from 0.2 - 3.0G(0) (G(0) = 2e(2)/h, where e is the charge of an electron and h is Planck's constant), even for the same width, a single atom.