Stony Brook University graduate student Qiang Zhu, together with Professor of Geosciences and Physics, Artem R. Oganov, postdoc Andriy O. Lyakhov and their colleagues from the University de Oviedo in Spain, have predicted three new forms of carbon, the findings of which were published in a paper entitled “Denser than diamond: Ab initio search for superdense carbon allotropes,” in the June 7, 2011 online edition of Physical Review B. So far, each new found modification of carbon resulted in a scientific, technological revolution – the same could happen now, if scientists can find a way to synthesize these new forms of carbon.
Elemental carbon possesses a unique range of structures and properties – from ultrsoft graphite to superhard diamond, and also including elusive carbines, beautifully symmetric fullerenes, carbon nanotubes, and the recently established new form, M-carbon (the structure of which was predicted by Oganov in 2006). Properties of all these modifications of carbon are so interesting and so tunable that two Nobel prizes were awarded recently for their studies (the 1996 Chemistry and 2010 Physics awards).
Graphene is the densest two-dimensional material, with unique mechanical and electronic properties and having some electrons moving with near-light velocities and behaving as if they had zero mass. Diamond has set several records – it is not only the hardest known material, but also has denser packing of atoms than any other known three-dimensional material. When doped by boron, diamond displays superconductivity and is the only know materials simultaneously displaying superhardness and superconductivity.
Now Zhu, Oganov, and their colleagues propose three new structures of carbon, which should be more than 3% denser than diamond. Greater density means that electrons should have a higher kinetic energy (that is, move faster). Calculations of Zhu et al. show that the new modifications are almost as hard as diamond, but do not exceed its hardness. Their electronic properties are very diverse, with the band gap ranging from 3.0 eV to 7.3 eV. Band gap is the minimum separation in energy between occupied and unoccupied electronic orbitals and is the most important characteristic of the electronic structure of materials. Such a wide range of band gaps implies the possibility of tuning the electronic properties. The band gap of 7.3 eV predicted for the tP12 modification is the largest value for all forms of carbon.
Other interesting properties include ultralow compressibility – when subjected to pressure, the new forms of carbon will contract less than most materials (even slightly less than diamond, the current record holder). They have higher refractive indices and stronger light dispersion than diamond – which means better brilliance and color effects than those displayed by diamond. “Carbon is an inexhaustible element in its chemical diversity and in the multitude of its physical applications”, says Professor Oganov. “If these predicted forms of carbon can be synthesized, they may find important technological roles”. Researchers believe that the new forms of carbon, thanks to their high densities, could be synthesized by shock compression of low-density modifications, or by directed growth on substrate.
Figure caption: Crystal structure of one of the superdense forms of carbon predicted by Zhu et al.
| Newswise Science News
Physics, photosynthesis and solar cells
01.12.2016 | University of California - Riverside
New process produces hydrogen at much lower temperature
01.12.2016 | Waseda University
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy