Microwave properties of platinum nanoparticle films

The electrical properties of platinum (Pt) nanoparticle films have been investigated experimentally using a microwave coaxial reflectance probe up to 6 GHz, for films composed of 26 nm and 11 nm particles. Larger particle films exhibit a conductive response, but with conductivity hugely suppressed (by a factor of >10⁵) compared to bulk Pt. Smaller particle films exhibit an even greater suppression of conductivity and a predominantly capacitive response above 1 GHz. The overriding factor in reduced conductance for smaller particles is the inter-grain contact resistance, which increases rapidly as particle size reduces.