Maxwell-Garnett theory extended for Cu–PbI_2 cermets

Abstract

The Maxwell-Garnett theory extended to include the shape factor and the size of the metal particles embedded in a dielectric matrix is proposed to explain the observed optical constants of a Cu–PbI2 cermet material. Both the shape factor and size of the particles are obtained by a separate fit of the real and imaginary parts of the measured dielectric constant. These geometrical parameters, once determined for a particular wavelength, can be used to derive the optical constants throughout the visible spectrum. Fairly good agreement is observed for a volume fraction ranging from 0 to 12%. Alternatively, the method derived in this paper can serve as a test for various theories proposed to predict the optical properties of composite materials.