These tiny wires have important dual-properties: super-strength and stretchiness. It is this mix of properties that have got University of Vermont researchers excited. These properties hold the key to innovations like one day taking a smartphone and folding it in half to store away in a pocket, and later taking the device out, unfolding it while maintaining full functionality.
With the creation of the wires, the most common methods for nanoparticle synthesis fall under the category of wet chemistry (what is termed the nucleation of particles within a solution).
The touchscreens of mobile devices today are made from ceramics. Developments have improved screens to the point where they are conductive and transparent. The downside is that they are a not flexible. To overcome this, work by Professor Frederic Sansoz has shown that by using seller only a few hundred atoms thick wires can be made that are strong and which can stretch much like a piece of gum. Moreover, when the silver wire is fashioned into a mesh it will conduct current and allow light to shine through. This strange property with silver, which was not previously known of, only happens at a very small scale. In essence, very small, but solid, silver crystals have a liquid-like behavior. This fluidity remains even at room temperature.
The reason this happens is due to the space that exists between the crystals at the size of 10 to 40 nanometers. The gap was observed using both an electron microscope and atomic level models on a supercomputer. The analysis showed that two mechanisms coexist at the same time: greater strength (where smaller results in the structure becoming stronger) and flexibility. The flexibility occurs due to diffusion which overcomes the defects in the molecular structure that arise from the wire being pulled. Instead of snapping, as most materials would, the wires effectively self-heal. Each wire can be stretched over 200 percent without a defect occurring.
The new discovery should lead to the creation of flexible touchscreens for use with new generation mobile devices like tablets and smartphones. The research provides technologists with the target size for creating silver wires for touchscreen development and the possibility of the completely foldable smartphone.
The research is published in the journal Nature Materials, under the heading “Slip-activated surface creep with room-temperature super-elongation in metallic nanocrystals.”
