Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Wandering heat: Anomalous heat distribution in one-dimensional systems

12.02.2014
According to Fourier’s law, heat spreads evenly throughout a system. For two- and one-dimensional objects such as films or the finest of wires, however, other rules seem to apply. NIM scientists have now pinned these down.

Just as ember spreads through a piece of coal, heat principally diffuses at a constant rate. The corresponding physical law known as Fourier’s law was already established 200 years ago.


Uniform spreading of heat ceases in low dimensions

Later, scientists came to the conclusion that other rules must apply to the distribution of heat in two- or one-dimensional objects such as films or very fine wires. Respective evidence was provided, for example, by experiments with carbon nanotubes or organic molecular chains, where thermal conductivity was not only dependent on the object’s material but also on its size, or rather its length.

This means that in some materials thermal conductivity increases with the object’s length, while in others it decreases. However, no one has so far been able to derive a physical law similar to Fourier’s law from these observations.

Together with international colleagues, NIM physicist Prof. Peter Hänggi (University of Augsburg) and his team have now gone one step further in the quest for such a law. The scientists have for the first time established a universally valid mathematical connection between object-size-dependent thermal conductivity and the corresponding anomalous rate of heat diffusion.

The insights thus gained allow scientists to devise hybrid materials which display entirely new thermal properties in one- or two-dimensional form. They exploit the fact that in these cases the rate of heat diffusion can be very high in some material compositions and extremely low in others. This is to say that one material allows heat to travel through it very quickly, while another functions as thermal insulator. The theoretical calculations are of particular interest for objects at nanoscale, whose thermal behavior is hard to measure in experiments. Currently, nanostructures composed of carbon materials which are to serve as phononic diodes or heat storage systems (memory) are simulated by computer models. Analogous to electronic components, these elements can then be used to conduct information processing.

“The exploration of heat diffusion in low-scale dimensions is only just beginning and certainly holds many surprises – as well as a huge potential”, explains Peter Hänggi. “The ubiquitous detrimental thermal losses, for example, can be used to beneficial effect for functional materials or phononic information processing. Maybe, in the distant future, the dream of a computer functioning with waste heat will come true.”

Publication:

Anomalous Heat Diffusion by Sha Liu, Peter Hänggi, Nianbei Li, Jie Ren, and Baowen Li. Phys. Rev. Lett. 112: 040601 (2014)

http://prl.aps.org/abstract/PRL/v112/i4/e040601

Contact person:

Prof. Peter Hänggi
Chair of Theoretical Physics I
Institute of Physics
University of Augsburg
86135 Augsburg, Germany
Tel: +49 821 598-3250
Hanggi@physik.uni-augsburg.de

Klaus P. Prem | idw
Further information:
http://www.nano-initiative-munich.de
http://www.uni-augsburg.de

More articles from Physics and Astronomy:

nachricht Fast and Accurate 3-D Imaging Technique to Track Optically-Trapped Particles
24.04.2015 | Korea Advanced Institute of Science and Technology

nachricht Tau Ceti: The next Earth? Probably not
23.04.2015 | Arizona State University

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fast and Accurate 3-D Imaging Technique to Track Optically-Trapped Particles

KAIST researchers published an article on the development of a novel technique to precisely track the 3-D positions of optically-trapped particles having complicated geometry in high speed in the April 2015 issue of Optica.

Daejeon, Republic of Korea, April 23, 2015--Optical tweezers have been used as an invaluable tool for exerting micro-scale force on microscopic particles and...

Im Focus: NOAA, Tulane identify second possible specimen of 'pocket shark' ever found

Pocket sharks are among the world's rarest finds

A very small and rare species of shark is swimming its way through scientific literature. But don't worry, the chances of this inches-long vertebrate biting...

Im Focus: Drexel materials scientists putting a new spin on computing memory

Ever since computers have been small enough to be fixtures on desks and laps, their central processing has functioned something like an atomic Etch A Sketch, with electromagnetic fields pushing data bits into place to encode data.

Unfortunately, the same drawbacks and perils of the mechanical sketch board have been just as pervasive in computing: making a change often requires starting...

Im Focus: Exploding stars help to understand thunderclouds on Earth

How is lightning initiated in thunderclouds? This is difficult to answer - how do you measure electric fields inside large, dangerously charged clouds? It was discovered, more or less by coincidence, that cosmic rays provide suitable probes to measure electric fields within thunderclouds. This surprising finding is published in Physical Review Letters on April 24th. The measurements were performed with the LOFAR radio telescope located in the Netherlands.

How is lightning initiated in thunderclouds? This is difficult to answer - how do you measure electric fields inside large, dangerously charged clouds? It was...

Im Focus: On the trail of a trace gas

Max Planck researcher Buhalqem Mamtimin determines how much nitrogen oxide is released into the atmosphere from agriculturally used oases.

In order to make statements about current and future air pollution, scientists use models which simulate the Earth’s atmosphere. A lot of information such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

HHL Energy Conference on May 11/12, 2015: Students Discuss about Decentralized Energy

23.04.2015 | Event News

“Developing our cities, preserving our planet”: Nobel Laureates gather for the first time in Asia

23.04.2015 | Event News

HHL's Entrepreneurship Conference on FinTech

13.04.2015 | Event News

 
Latest News

Electrons Move Like Light in Three-Dimensional Solid

24.04.2015 | Materials Sciences

Connecting Three Atomic Layers Puts Semiconducting Science on Its Edge

24.04.2015 | Materials Sciences

Understanding the Body’s Response to Worms and Allergies

24.04.2015 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>