Three years ago, physicists from Luxembourg had theoretically predicted the unusual characteristics of a particular composite material. The calculations could now be confirmed by experiment in cooperation with the ‘Centre de Recherche Paul Pascal’ in Bordeaux, France, and resulted in the discovery of the high-k-material, which might enable the production of better energy storage devices and has interested the plastics producing industry.
The earlier calculations made by the team around Tanja Schilling, professor of physics at the University of Luxembourg, were at first regarded as bad news for the field of materials research: they indicated that certain compound materials made of polymers and flaky graphene, unlike those made of polymers and carbon nanotubes, did not increase the conductivity of the material to the degree that was generally expected until then. The conclusion was surprising at the time which questioned the use of graphene in order to increase conductivity.
The prediction, however, has now led to a promising discovery: the effect that put the conductivity of the plastics-graphene-compound into question, causes it to have remarkable dielectric properties which means that it is possible to generate a strong electric field inside of it – the fundamental property for the production of efficient capacitors. These are tiny components that can store energy statically and occur in almost all electronic devices, where they act as voltage regulators or information storage, among other things. Computers, for example, contain billions of those.
The special dielectric properties of the compound material occur as a result of its liquid crystal properties impeding the arrangement of the graphene flakes into a conducting structure. So when there is an electric current, it does not flow directly through the compound, but instead generates a strong electric field. While in other compound materials the current permeable effect is the dominant one, the Luxembourg physicists could demonstrate mathematically that, in this case, the liquid crystal properties play the major role and are responsible for the unexpected electric properties.
The chemicals company Solvay, partner of the research project, now wants to continue the research around the new high-k-material, aiming to produce synthetics for particularly efficient capacitors and further applications in the future.
The article “Graphene Liquid Crystal Retarded Percolation for New High-k Materials”, Jinkai Yuan, Alan Luna, Wilfrid Neri, Cécile Zakri, Tanja Schilling, Annie Colin & Philippe Poulin, is published in “Nature Communications” (DOI: 10.1038/ncomms9700).
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