A group of scientists from Russia, the USA and China, led by Artyom Oganov from the Moscow Institute of Physics and Technology (MIPT), using computer generated simulation have predicted the existence of a new two-dimensional carbon material, a "patchwork" analogue of graphene called phagraphene. The results of their investigation were recently published in the journal Nano Letters.
"Unlike graphene, a hexagonal honeycomb structure with atoms of carbon at its junctions, phagraphene consists of penta-, hexa- and heptagonal carbon rings. Its name comes from a contraction of Penta-Hexa-heptA-graphene," says Oganov, head of the MIPT Laboratory of Computer Design.
Two-dimensional materials, composed of a one-atom-thick layer, have attracted great attention from scientists in the last few decades. The first of these materials, graphene, was discovered in 2004 by two MIPT graduates, Andre Geim and Konstantin Novoselov. In 2010 Geim and Novoselov were awarded the Nobel Prize in physics for that achievement.
Due to its two-dimensional structure, graphene has absolutely unique properties. Most materials can transmit electric current when unbound electrons have an energy that corresponds to the conduction band of the material.
When there is a gap between the range of possible electron energies, the valence band, and the range of conductivity (the so-called forbidden zone), the material acts as an insulator. When the valence band and conduction band overlap, it acts a conductor, and electrons can move under the influence of electric field.
In graphene each carbon atom has three electrons that are bound to electrons in neighboring atoms, forming chemical bonds. The fourth electron of each atom is "delocalized" throughout the whole graphene sheet, which allows it to conduct electrical current.
At the same time, the forbidden zone in the graphene has zero width. If you plot the electron energy and their location in graph form, you get a figure resembling an hour glass, i.e. two cones connected by vertices. These are known as Dirac cones.
Due to this unique condition, electrons in graphene behave very strangely: all of them have one and the same velocity (which is comparable to the velocity of light), and they possess no inertia. They appear to have no mass.
And, according to the theory of relativity, particles traveling at the velocity of light must behave in this manner. The velocity of electrons in graphene is about 10 thousand kilometers a second (electron velocities in a typical conductor vary from centimeters up to hundreds of meters per second).
Phagraphene, discovered by Oganov and his colleagues through the use of the USPEX algorithm, as well as graphene, is a material where Dirac cones appear, and electrons behave similar to particles without mass.
"In phagraphene, due to the different number of atoms in the rings, the Dirac cones are 'inclined.' That is why the velocity of electrons in it depends on the direction. This is not the case in graphene. It would be very interesting for future practical use to see where it will be useful to vary the electron velocity," Artyom Oganov explains.
Phagraphene possesses all the other properties of graphene that allows it to be considered an advanced material for flexible electronic devices, transistors, solar batteries, display units and many other things.
Phagraphene: A Low-Energy Graphene Allotrope Composed of 5-6-7 Carbon Rings with Distorted Dirac Cones
Stanislav Goryachev | EurekAlert!
Scientists channel graphene to understand filtration and ion transport into cells
11.12.2017 | National Institute of Standards and Technology (NIST)
Successful Mechanical Testing of Nanowires
07.12.2017 | Helmholtz-Zentrum Geesthacht - Zentrum für Material- und Küstenforschung
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
An interdisciplinary group of researchers interfaced individual bacteria with a computer to build a hybrid bio-digital circuit - Study published in Nature Communications
Scientists at the Institute of Science and Technology Austria (IST Austria) have managed to control the behavior of individual bacteria by connecting them to a...
Physicists in the Laboratory for Attosecond Physics (run jointly by LMU Munich and the Max Planck Institute for Quantum Optics) have developed an attosecond electron microscope that allows them to visualize the dispersion of light in time and space, and observe the motions of electrons in atoms.
The most basic of all physical interactions in nature is that between light and matter. This interaction takes place in attosecond times (i.e. billionths of a...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
11.12.2017 | Physics and Astronomy
11.12.2017 | Earth Sciences
11.12.2017 | Information Technology