A comprehensive review on effective medium theories to find effective dielectric constant of composites

We present here a selective and focused review of various Effective Medium Theories (EMT) with their progressive developments, and different mixture formulae used to calculate one of the most important optical constants, i.e. effective permittivity, for different composites. First, we visit the well-known Maxwell Garnett (MG) EMT and its variants. Thereafter, we discuss MG-EMT for the inclusions such as bi-anisotropic materials, carbon nanotube, uniaxial, and anisotropic materials. Then we emphasise the Bruggeman (Br) EMT and its variants. We have also discussed Br-EMT for uniaxial inclusions. In the next section, we analyse Bragg-Pippard (BP) EMT for anisotropic dielectric homogenized composite medium and for bi-anisotropic system. Next, we discuss on Strong Property Fluctuation Theory (SPFT) for bi-anisotropic ellipsoidal inclusions. Following this, we consider EMT for dielectric-magnetic materials, and for thin multilayer structures. Finally, we discuss different mixture formulae used for colloidal solutions, gas mixtures, solvent mixtures, and electrolyte solutions.