(275b) Creating Conductive Copper-Silver Bimetallic Nanostructured Coatings Using a High Temperature Reducing Jet Aerosol Reactor

We present here the high temperature flame-based synthesis of non-oxide nanoparticle hybrid films using a high temperature reducing jet (HTRJ) reactor. We synthesized bimetallic copper-silver nanostructured films by direct deposition of nanoparticles produced within the HTRJ reactor. The HTRJ process allows us to decouple the flame chemistry from the nanoparticle formation chemistry. The alloy and bi-component nanoparticles have potential applications in conductive ink formulations for printed electronics, in antibacterial coatings, and in heat-transfer fluids. Silver nanoparticles have been widely used in conductive nanoink formulations as well as in RFID technology. This is not only because silver has high room temperature electrical conductivity (~6×10⁷ S/m), but also because its oxide has appreciable conductivity (of order 10⁶ S/m). However, due to high cost of silver metal, researchers are looking for alternatives. Copper has electrical conductivity similar to that of silver (~6×10⁷ S/m) and is much lower in cost than silver, but oxidizes rapidly in the presence of atmospheric oxygen. Here, we report the single step direct synthesis of copper-silver nanostructured particles and films using the HTRJ flame-based process. The objective of this work was to synthesize a bimetallic coating using copper and silver with minimal use of silver to lower the cost and to meet the desired industrial window of electrical conductivity (> 100 S/m) for the aforementioned applications. The advantages of HTRJ technology stem from the use of low-cost, water soluble nitrate precursors, and a low-cost energy source in a continuous and environmentally benign process. The metal films were thermophoretically deposited on soda lime glass. In this presentation, we will describe the HTRJ process briefly, and then focus on the synthesis and characterization of bimetallic copper-silver films on glass substrates. The hybrid copper-silver coating had a high bulk electrical conductivity of 10⁴ S/m at 40 wt% Ag. The effect of silver concentration in the mixed copper-silver films on the electrical conductivity of these coatings was studied systematically.