Effective permittivity extraction of dielectric nano-powder and nano-composite materials: Effects of packing densities and mixture compositions

This paper investigates the electrical characteristics of nano-particle-based pulverized materials. A measurement setup is developed to extract the electrical properties of the composite material in its powder form. Numerical simulations are also carried out to examine and analyze the effects of embedded metallic particles in a dielectric host medium. The experimental results present the role of the packing density of the powder on the dielectric constant. The developed techniques are applied to extract the electrical properties of nano-dielectric particles mixed with nano/micro-metallic particles; examples of these composites include micro particles of copper are mixed with dry powder of nano particles of alumina and a mixture of semiconducting and metallic carbon nanotubes. The presented results show that the real part of the dielectric constant may be considerably increased with the increase of conducting nano-particles ratio. The percolation theory is used to provide a physical explanation of the observed enhancement of the effective permittivity below percolation threshold.