Physicists at the Max Planck Institute for Polymer Research show unlimited heat conduction in graphene.
Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz and the National University of Singapore have attested that the thermal conductivity of graphene diverges with the size of the samples. This discovery challenges the fundamental laws of heat conduction for extended materials.
Davide Donadio, head of a Max Planck Research Group at the MPI-P, and his partner from Singapore were able to predict this phenomenon with computer simulations and to verify it in experiments. Their research and their results have now been presented in the scientific journal "Nature Communications".
"We recognized mechanisms of heat transfer that actually contradict Fourier’s law in the micrometer scale. Now all the previous experimental measurements of the thermal conductivity of graphene need to be reinterpreted. The very concept of thermal conductivity as an intrinsic property does not hold for graphene, at least for patches as large as several micrometers", says Davide Donadio.
Are material constants alterable after all?
The French physicist Joseph Fourier had postulated the laws of heat propagation in solids. Accordingly, thermal conductivity is an intrinsic material property that is normally independent of size or shape. In graphene, a two-dimensional layer of carbon atoms, it is not the case, as our scientists now found out. With experiments and computer simulations, they found that the thermal conductivity logarithmically increases as a function of the size of the graphene samples: i.e., the longer the graphene patches, the more heat can be transferred per length unit.
This is another unique property of this highly praised wonder material that is graphene: it is chemically very stable, flexible, a hundred times more tear-resistant than steel and at the same time very light. Graphene was already known to be an excellent heat conductor: The novelty here is that its thermal conductivity, which was so far regarded as a material constant, varies as the length of graphene increases. After analyzing the simulations, Davide Donadio found that this feature stems from the combination of reduced dimensionality and stiff chemical bonding, which make thermal vibration propagate with minimal dissipation at non-equilibrium conditions.
Optimum cooling for nanoelectronics
In the micro- and nano-electronics, heat is the limiting factor for smaller and more efficient components. Therefore, materials with virtually unlimited thermal conductivity hold an enormous potential for this kind of applications. Materials with outstanding electronic properties that are self-cooling too, as graphene might be, are the dream of every electronics engineer.
Davide Donadio, an Italian-born researcher, already dealt with nanostructures of carbon, crystallization processes and thermoelectric materials during his studies in Milan, his research stays at the ETH Zurich (Switzerland) and at the University of California, Davis (USA). Since 2010, he has been investigating, among others, thermal transport in nanostructures using theoretical physics and simulating the atomic behavior of substances with his Max Planck Research Group at the MPI-P.
http://www.mpip-mainz.mpg.de/news/thermal_conductivity - the press release and original publication
http://www.mpip-mainz.mpg.de/theory_nanostructures - informatio about Davide Donadio and his research
http://www.mpip-mainz.mpg.de/home/en - Max Planck Institute for Polymer Research
Stephan Imhof | Max-Planck-Institut
Absorbing acoustics with soundless spirals
10.02.2016 | American Institute of Physics
Hot Science of the Cold Universe
10.02.2016 | Max-Planck-Institut für Radioastronomie
Atomic clock experts from the Physikalisch-Technische Bundesanstalt (PTB) are the first research group in the world to have built an optical single-ion clock which attains an accuracy which had only been predicted theoretically so far. Their optical ytterbium clock achieved a relative systematic measurement uncertainty of 3 E-18. The results have been published in the current issue of the scientific journal "Physical Review Letters".
Atomic clock experts from the Physikalisch-Technische Bundesanstalt (PTB) are the first research group in the world to have built an optical single-ion clock...
The University of Würzburg has two new space projects in the pipeline which are concerned with the observation of planets and autonomous fault correction aboard satellites. The German Federal Ministry of Economic Affairs and Energy funds the projects with around 1.6 million euros.
Detecting tornadoes that sweep across Mars. Discovering meteors that fall to Earth. Investigating strange lightning that flashes from Earth's atmosphere into...
Physicists from Saarland University and the ESPCI in Paris have shown how liquids on solid surfaces can be made to slide over the surface a bit like a bobsleigh on ice. The key is to apply a coating at the boundary between the liquid and the surface that induces the liquid to slip. This results in an increase in the average flow velocity of the liquid and its throughput. This was demonstrated by studying the behaviour of droplets on surfaces with different coatings as they evolved into the equilibrium state. The results could prove useful in optimizing industrial processes, such as the extrusion of plastics.
The study has been published in the respected academic journal PNAS (Proceedings of the National Academy of Sciences of the United States of America).
Exceeding critical temperature limits in the Southern Ocean may cause the collapse of ice sheets and a sharp rise in sea levels
A future warming of the Southern Ocean caused by rising greenhouse gas concentrations in the atmosphere may severely disrupt the stability of the West...
Indications of light-induced lossless electricity transmission in fullerenes contribute to the search for superconducting materials for practical applications.
Superconductors have long been confined to niche applications, due to the fact that the highest temperature at which even the best of these materials becomes...
09.02.2016 | Event News
02.02.2016 | Event News
26.01.2016 | Event News
10.02.2016 | Life Sciences
10.02.2016 | Earth Sciences
10.02.2016 | Physics and Astronomy