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 Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover

nachricht First transcription atlas of all wheat genes expands prospects for research and cultivation
17.08.2018 | Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

Robots as Tools and Partners in Rehabilitation

17.08.2018 | Information Technology

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>