Nitrogen under Extreme Conditions: From Fundamental Physics to Novel Functional Materials

Lead Research Organisation: University of Edinburgh
Department Name: Sch of Physics and Astronomy

Abstract

The technological developments seen in the last 400 years largely rest on incremental increases of the understanding of the fundamental behaviour of matter, in turn exploited to enable the formation of breakthrough functional materials. In our modern day societies, two of the most important class of materials are high energy density and superhard solids. High energy density materials (HEDMs) are employed as mining explosives-with hundreds of millions of tons annually used to extract essential minerals from the Earth-and as rocket fuel. They are the subject of intense research to find higher performance and non-polluting alternatives. On the other hand, superhard materials represent a growing multibillion international market and are indispensable for a wide range of applications, from machining tools to medical prosthetics, passing through aerospace, optics and even jewellery. While diamond is considered the sovereign superhard material, it low abrasiveness and chemical stability makes it inadequate for a number of applications for which an alternative must be found.

The remarkable characteristics of nitrogen make it the ideal element for new breakthrough HEDMs and superhard materials. Indeed, covalent nitrogen-nitrogen single bonds are the most energetic bonds among all elements, storing and releasing close to ten times more energy than the current best HEDMs. Nitrogen HEDMs are entirely eco-friendly. At the same time, nitrogen covalent bonds are also ultra-stiff, enabling the formation of superhard solids. While the exceptional potential of nitrogen for technological materials has been known for decades, classical approaches have proven inadequate in producing attractive nitrogen-rich compounds. In recent years, a new parameter for material synthesis has established itself as a top contender for achieving the sought-after nitrogen-based industrial materials: pressure. Indeed, compression to millions of times the atmospheric pressure radically changes the behaviour of matter and favours new and exotic atomic arrangements that are predominantly inaccessible otherwise, such as the greatly desirable high energy and ultra-stiff nitrogen covalent bonds.

This research project aims at exploiting the high pressure approach to harness the tremendous potential of nitrogen to produce new technological materials. As a crucial first step, the physico-chemical forces governing the high pressure behaviour of molecular nitrogen (N2) will be experimentally investigated. Then, in a collaborative effort with theorists, a new theoretical framework will be elaborated to address the shortcomings of first-principles predictions and significantly increase their accuracy-essential for engineering novel nitrogen-based functional materials. In a second step, the most promising nitrogen binary systems for forming high energy density as well as superhard solids will be experimentally studied. All pressure-produced compounds will be characterized to determine their exact nature and properties, as well as to establish their potential use as industrial materials. This work can only be successfully achieved by exploiting a recently developed technique: synchrotron single-crystal X-ray diffraction from polycrystalline samples (SC-XRDp). This research project will take place at the Centre for Science at Extreme Conditions (CSEC) of the University of Edinburgh-a world-renowned institution in the field of high pressure sciences with the necessary tools and expertise required for the successful realization of this research project.

The pressure parameter promises to be key to finally unravel the full potential of nitrogen. Exploiting a novel experimental method, the boundaries of our understanding of matter under extreme conditions will be pushed further back than ever before; ushering a new era for the design of novel functional materials. The discovered solids will undoubtedly play a pivotal role in the upcoming decades' technological breakthroughts.

Publications

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Laniel D (2022) Revealing Phosphorus Nitrides up to the Megabar Regime: Synthesis of a'-P3 N5, d-P3 N5 and PN2. in Chemistry (Weinheim an der Bergstrasse, Germany)

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Akbar FI (2023) High-pressure synthesis of dysprosium carbides. in Frontiers in chemistry

 
Description During this first year of this FLF, great progress was already accomplished. Chief among these is the synthesis and characterization of a long-sought-after nitrogen-only unit, a hexazine ring, [N6]4- (i.e. six nitrogen atoms forming a flat ring). This hexaxine unit is extremely energetic and environmentally friendly, making it a great candidate as a building block for new high-energy density materials. Moreover, this hexazine ring was found to be aromatic--an electronic property that enhances the stability of the species. Produced under high-pressure conditions, this unit couldn't yet be recovered to ambient conditions. However, we are actively working on forming it in a system that will allow recoverability to ambient conditions.

With regards to ultraincompresible and superhard nitrogen-based compounds, we have also made significant progress. Indeed, C-N compounds have been produced under pressure and found to have a hardness comparable to that of diamond on top of having other properties lacking in diamond. These materials could eventually be used for smart cutting tools, protective coatings, prosthetics, etc. These results are currently submitted to a journal but are available on the arXiv platform.

The more fundamental aspect of my FLF is also going along smoothly, with very promising results having been achieved while studying the high-pressure high-temperature phase diagram of molecular nitrogen.

All of these accomplishments were realized with two very close groups of collaborators. One group is located at Linköping University (Sweden), and help us with theoretical calculations. The other group is at the University of Bayreuth (Germany), helping with their experimental expertise in producing large sample volumes.
Exploitation Route We hope that the new materials we have recently produced will eventually be taken to an industrial level. However, the scaling up requires considerable work, resources, and a different set of expertise. We will need to seek out new collaborators to help out with this aspect--hopefully industrial groups. Assuming a successful scaling up, these materials could replace diamond as cutting tools and protective coatings.

Otherwise, the discovery of the hexazine ring will undoubtedly help promote research in environmentally friendly nitrogen-based high-energy density materials.
Sectors Aerospace

Defence and Marine

Chemicals

Energy

 
Description EPSRC IAA Innovation Competition
Amount £2,474 (GBP)
Funding ID EPSRC IAA PV095 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 08/2023 
End 04/2024
 
Description French Alternative Energies and Atomic Energy Commission 
Organisation French Alternative Energies and Atomic Energy Commission
Country France 
Sector Public 
PI Contribution My team and I have contributed through our expertise in solving structures of novel compounds under extreme pressure and temperature conditions.
Collaborator Contribution The CEA team has provided us with high quality samples that are extremely hard to produce.
Impact As of yet, there are no outputs.
Start Year 2022
 
Description Institute of Metallurgy and Materials Science 
Organisation Polish Academy of Sciences
Country Poland 
Sector Public 
PI Contribution Collaborators from the Institute of Metallurgy and Materials Science and I are collaborating on investigating the behavior of metallic glasses under extreme pressure and temperature conditions.
Collaborator Contribution I am preparing the high pressure apparatus (i.e. the diamond anvil cells) that will be used to apply pressure on the metallic glasses samples prepared by the team at the Institute of Metallurgy and Materials Science. I helped write the European Synchrotron Research Facility beamtime application--which turned out to be successful. I will be leading the beamtime on this project.
Impact At the moment, the main outcome was obtaining beamtime at the ESRF to study the metallic glasses under high pressure and temperatures.
Start Year 2023
 
Description University of Bayreuth 
Organisation University of Bayreuth
Country Germany 
Sector Academic/University 
PI Contribution My team and I have provided support during experiments at particle accelerators (i.e. synchrotrons). We have also contributed to the synthesis and characterization of new solids formed under extreme pressure and temperature conditions.
Collaborator Contribution The University of Bayreuth team has provided assistance during particle accelerator experiments. They have also performed large volume press experiments on our behalf.
Impact Since 2022, fifteen peer-reviewed articles have been published as a result of our collaboration.
Start Year 2022
 
Description University of Linköping 
Organisation Linkoping University
Country Sweden 
Sector Academic/University 
PI Contribution My team and I have provided experimental data, namely structure models of novel compounds produced under extreme pressures and temperatures to the Linköping team.
Collaborator Contribution The Linköping team has done density functional theory (DFT) calculations on the novel compounds we have synthesized under extreme pressure and temperature conditions. These DFT calculations provide crucial information about the properties of the produced solids. Given the extremely small sample sizes that we are usually working with, i.e. on the order of micrograms, these material properties cannot be easily obtained through experiments.
Impact Eleven publications have resulted from this collaboration. This is a multi-disciplinary collaboration between experimental condensed matter sciences and computational condensed matter sciences.
Start Year 2022
 
Description University of Munich 
Organisation Ludwig Maximilian University of Munich (LMU Munich)
Country Germany 
Sector Academic/University 
PI Contribution My team and I have performed high pressure high temperature particle accelerator experiments on samples produced by the LMU team. With these samples, we have synthesized novel solids and characterized them using single-crystal X-ray diffraction.
Collaborator Contribution The LMU team has provided us with high-quality precursors that we use in our high-pressure experiments.
Impact Thus far, two papers have resulted from this collaboration.
Start Year 2022
 
Description Deutsches Elektronen-Synchrotron (DESY) Photon Science Users' Meeting 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Deutsches Elektronen-Synchrotron (DESY) Photon Science Users' Meeting brings users from different research communities using synchrotron radiation. My presentation was given to about 25 people, including researchers, DESY policymakers, post-graduate students and focused on explaining my research and the role that synchrotron radiation plays in it.
This gave rise to questions from individuals from different fields and highlighted possible crossfield research.
Year(s) Of Engagement Activity 2023
URL https://indico.desy.de/event/36974/
 
Description General public press release on recent publication--novel aromatic [N6]4- species 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact I wrote a press release for an article recently published in Nature Chemistry that was done through my FLF funding. This press release was aimed at the general public. It is hard to estimate how many individuals this story reached, but it was picked up by 11 distinct media outlets across Europe, the Americas and Asia.
Year(s) Of Engagement Activity 2023
URL https://www.ph.ed.ac.uk/news/2023/synthesis-and-characterization-of-a-new-nitrogen-aromatic-species-...
 
Description General public press release on recent publication--novel lanthanum hydrides 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact I wrote a press release for an article recently published in Nature Communications that was done through my FLF funding. This press release was aimed at the general public. It is hard to estimate how many individuals this story reached, but it was picked up by six distinct media outlets across Europe.
Year(s) Of Engagement Activity 2023
URL https://www.ph.ed.ac.uk/news/2022/progress-towards-hydrogen-based-solid-superconductivity-22-12-01
 
Description General public press release on recent publication--novel ultrahard carbon nitrides materials 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact I wrote a press release for an article recently published in Advanced Materials that was done through my FLF funding. This press release was aimed at the general public. The story had a huge outreach, being published in a total of 192 media outlets across the world. It has an almetric value of 1473; a huge number.
Year(s) Of Engagement Activity 2023
URL https://www.ed.ac.uk/news/2023/ultra-hard-material-to-rival-diamond-discovered
 
Description General public press release on recent publication--the structure of the zeta-N2 allotrope 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact I wrote a press release for an article recently published in Nature Communications that was done through my FLF funding. This press release was aimed at the general public. It is hard to estimate how many individuals this story reached, but it was picked up by six distinct media outlets across Europe.
Year(s) Of Engagement Activity 2023
URL https://www.ph.ed.ac.uk/news/2023/scientists-unlock-the-secrets-of-nitrogens-unique-z-n2-solid-phase...
 
Description IUCr High-Pressure Workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact The IUCr High-Pressure Workshop was meant to provide an opportunity to discuss the most recent developments in the field of high-pressure crystallography with crystallographers of other disciplines. This cross-disciplinary workshop gave rise to conversations helpful for the further development of the high-pressure crystallography community. I gave a talk presenting my research, which involves the latest developments in high-pressure crystallography.
Year(s) Of Engagement Activity 2022
URL https://gsecars.uchicago.edu/education-and-outreach/2022-iucr-high-pressure-workshop-advanced-high-p...
 
Description QUANTUM MATERIALS WORKSHOP 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact I presented the latest developments in the field of synchrotron high-pressure experiments to researchers from another discipline, i.e. that of quantum materials. This was followed by discussions that served to establish how the two disciplines are interrelated and how cross-field research could be approached.
Year(s) Of Engagement Activity 2022
URL https://www.esrf.fr/home/events/conferences/2022/QuantumMaterials.html