An analytical solution is constructed for the homogenized (i.e., macroscopic) dielectric response of particulate composites comprising a random distribution of particles bonded to a matrix material through interphases of finite size that contain space charges. By accounting for interphasial charges, the solution is able to describe and explain both the extreme enhancement and the reduction of the dielectric response typically exhibited by emerging polymer nanoparticulate composites. More generally, the solution reveals that judicious manipulation of interphasial charges provides a promising path forward for the design of materials with exceptional dielectric properties.
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In this regard, it is important to emphasize that the vast majority of homogenization techniques and results currently available14 make critical use of the assumption that source terms (such as, for instance, space charges, body forces, and heat sources) oscillate only at the macroscale.
For definiteness, we restrict attention here to the case of isotropic microstructures and isotropic constitutive properties. However, the arguments apply more generally to particulate composites with anisotropic microstructures and anisotropic constitutive properties.21
Full experimental details together with a comprehensive set of electromechanical measurements will be reported elsewhere.
