Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists from MIPT gain insights into 'forbidden' chemistry

11.02.2016

Scientists have discovered what causes the stability of various compounds that are not commonly found in 'textbook' chemistry

Gabriele Saleh, a research fellow at MIPT, and Prof. Artem Oganov, a Laboratory Supervisor at MIPT and Professor at the Skolkovo Institute of Science and Technology (Skoltech), have discovered what causes the stability of various compounds that are not commonly found in 'textbook' chemistry.


The structures of 'textbook' NaCl (left) and 'forbidden' A3Y (A=Li, Na, K; Y= Cl, Br) (right) are shown.

Credit: MIPT press office

The reorganisation of the chemical interactions results in the stability of the 'new' structure of the compounds. The results of the study have been published in the journal Physical Chemistry & Chemical Physics.

Oganov and Saleh derived a simple model and formulated the basic principles of stability of 'forbidden' substances. In addition, the scientists updated the phase diagram of compounds formed by Na and Cl: they added one new compound, Na4Cl3, and two new phases of Na3Cl. The research was conducted using the USPEX algorithm combined with quantum mechanical calculations.

"We showed how the insights gained in the present study can be used to rationalize the stability of recently discovered high-pressure compounds," say the authors in their paper.

In a previous experiment, Oganov and his colleagues discovered several 'forbidden' compounds- Na3Cl, NaCl3, NaCl7,and even Na3Cl2. These compounds are only stable under extreme pressure (approximately 200,000 atmospheres) and they decompose under normal conditions on Earth. However, understanding how new compounds become stable under high pressure is of utmost importance for planetary science.

The principle that explains the unusual ratio of Na and Cl atoms in 'forbidden' compounds is that the number of interactions between Na and Cl atoms increases while interactions between sodium atoms break down.

The interactions between neighbouring atoms in a crystal are responsible for the structure and properties of the crystal (remember carbon and graphite).

Upon formation of these 'forbidden compounds', new Na-Cl interactions are formed at the expenses of Na-Na metallic bonds. The competition between these two bonding types, influenced by pressure, determines the peculiar structures of the newly discovered compounds.

In addition to explaining the stability of sodium subchlorides, Saleh and Oganov suggested that Na could be replaced by any alkali metal, and Cl could be replaced by any heavier halogen. As a result, the model can be used to study the properties of alkali subhalides and predict their stability.

The formation of alkali subhalides, and the mechanism responsible for it, were investigated by considering the reaction: 2Na +NaCl ->Na3Cl. Or more generally: 2A + AY -> A3Y (A=Li, Na, K; Y= F, Cl, Br). Along this reaction, additional bonds and interactions are formed and the coordination number (that is the number of interactions a given atom forms) of halogens increases.

The calculations made by Oganov and Saleh have demonstrated that in addition to the compounds discovered in 2013, Na4Cl3 is also stable, and Na3Cl has two new structures. The investigation of the stability of substances formed along the reaction 2A + AY -> A3Y (A=Li, Na, K; Y= F, Cl, Br) led the authors to predict that Li3Cl, Li3Br, and Na3Br are stable under pressure. All three of these subhalides have a structure similar to the structure of Na3Cl, which was discovered previously.

Each rule must have its exceptions - K3Br and K3Cl, for example, display completely different structures. The researchers demonstrated that this different behaviour can be traced back to potassium (K) having energetically accessible d-orbitals, which is not the case for lithium and sodium. Under pressure, these orbitals come into play and form different chemical bonds with respect to those observed in lithium and sodium compounds.

Computer-aided design of materials is a new and promising field of materials science. Thanks to modern computing facilities and algorithms, scientists are able to predict the structure and properties of compounds, which will significantly increase the speed and reduce the cost of manufacturing the materials of the future.

Media Contact

Valerii Roizen
press@mipt.ru
7-929-992-2721

 @phystech

http://mipt.ru/en/ 

Valerii Roizen | EurekAlert!

More articles from Life Sciences:

nachricht Water forms 'spine of hydration' around DNA, group finds
26.05.2017 | Cornell University

nachricht How herpesviruses win the footrace against the immune system
26.05.2017 | Helmholtz-Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>