Three-dimensionally periodic conductive nanostructures: network versus cermet topologies for metallic PBG

Highly periodic three-dimensional metallic mesh composites with silica have been prepared by micromolding synthetic opals using melts of metals and semimetals. These metallic photonic crystals show photonic and electronic properties, which strongly depend on their geometry. Network topology, created in a form of interconnected spherical cages of 200–400 nm diameter, shows a reflectivity peak in the infrared (IR) spectral range, due to a metallic photonic band gap (MPBG), reminiscent of plasmon edge of bulk metal, which is significantly shifted to longer wavelengths. On the other hand, a discontinuous topology of separated clusters in a matrix (so called cermet topology) obtained by three distinct techniques involved controlling the pressure and temperature of the melt during the infiltration process), do not show any MPBG. In the visible spectral range, bright sharp colors of Bragg scattering are observed from both topologies, which are more intense than in conventional, dielectric gem opals in agreement with computer modeling of light reflection from cermet metallo-dielectric photonic crystals. etallic PBG structures can be used as novel type IR reflectors, color mirrors and conductive electrodes having properties controlled by the topology of 3-D superstructure.