Particle size influence on the effective static dielectric constant of composite materials

Considering an actual collection of spherical particles dispersing in a medium, we study in detail the polarization of particles and the effective static dielectric constant by two general models. Particles embedded in a medium lead to core-shell structure. The shell is the interface layer between the particle and the medium. With the effect of the interface layer included, these models are exactly solved with some details for metallic particles and non-metallic particles, respectively. The effective static permittivity of the composite material is approximated by Maxwell-Garnett method. The significant change of the effective permittivity is given by a term in proportional to the volume ratio of the interface layer, which is big for nano-sized particles. The permittivity of the interface layer plays an important role in the dependence of the effective permittivity of the composite material on particle size.