Nanostructure-Level Modeling of Nonlinear Energy Storage in Polymer-Ceramic Nanocomposites

摘要

A critical issue in composite dielectrics is the prediction of the overall properties of the composite based on constituent properties. Given a microstructure or nanostructure of the composite,one would like to be able to predict,using computer simulations,the real and imaginary parts of the small-signal dielectric permittivity (? '?j),the energy storage at high electric fields,etc.,without resorting to free parameters. The ultimate goal is the complete modeling of composite materials for capacitors at the microstructure level,including both micro- and nanoscale features (individual particles,ensembles of particles in a matrix) and the truly nanoscopic features (interfacial effects,coatings,local dipolar interactions in surface layers,etc.). Such a capability would allow experimental synthesis to be focused on the most promising microstructural approaches,without the need to physically test each idea. It would also be critical for understanding tradeoffs between competing requirements,for example energy storage vs. breakdown. Within a specific class of micro- or nanostructures,the computational capability would provide explicit guidance to synthesis efforts,for example allowing the intelligent selection of particle shapes,loading fractions,surface coatings,and hierarchical assembly strategies. Finally,the computational techniques will provide a means of understanding experimental results on existing and new materials.