Effective dielectric response of composites containing uniaxial inclusions

An approach is proposed for the calculation of an effective dielectric func tion for a composite medium containing randomly oriented particles with uni axial polarisability (the medium is isotropic on average). A scalar renorma lised average polarisability of the particles is introduced, which takes co mplete account of the tensor nature of the dipole-dipole interaction betwee n them. Fluctuations originating from their random positions are treated in the spirit of the average T-matrix approximation. The renormalised polaris ability is related to the effective dielectric function via the Maxwell-Gar nett equation. The theory is illustrated by calculating the reflectivity an d absorption of a colloidal solution of hexagonal CdS particles.