Studies to unravel some underlying mechanisms in nanodielectrics

The intense interest in nanocomposites in the last few years results from the documented enhancements in mechanical, thermal and electrical properties that are possible when particulates of nanometric scale are embedded in a polymer matrix. It has become clear that the primary reason for these improvements is the dominance of the internal interfacial surfaces which characterizes nanodielectrics of this form. This contribution seeks to employ a plurality of experimental methods (dielectric spectroscopy, thermally-stimulated currents, divergent-field spectrally-resolved electroluminescence and absorption current measurements) to shed some light on the relevant mechanisms responsible for the electrical characteristics observed. A cross-linked polyethylene/SiO₂ system is used, where material formulation has allowed alteration of both the interfacial area (through particle size adjustment) and the chemical nature of the interface. The conclusion is reached, after assessment of the interrelationships between these techniques, that the internal surfaces at the interfaces have a profound effect on both the injection of charge and its subsequent migration through the structure.