Nav: Home

'Black nitrogen'

May 29, 2020

In the periodic table of elements there is one golden rule for carbon, oxygen, and other light elements. Under high pressures they have similar structures to heavier elements in the same group of elements. Only nitrogen always seemed unwilling to toe the line. However, high-pressure researchers of the University of Bayreuth have actually disproved this special status. Out of nitrogen, they have created a crystalline structure which under normal conditions occurs in black phosphorus and arsenic. The structure contains two-dimensional atomic layers, and is therefore of great interest for high-tech electronics. The scientists have presented this "black nitrogen" in "Physical Review Letters".

Nitrogen - an exception in the periodic system?

When you arrange the chemical elements in ascending order according to their number of protons, and look at their properties, it soon becomes obvious that certain properties recur at large intervals ("periods"). The periodic table of elements brings these repetitions into focus. Elements with similar properties are placed one below the other in the same column, and thus form a group of elements. At the top of a column is the element that has the fewest protons and the lowest weight compared to the other group members. Nitrogen heads element group 15, but was previously considered the "black sheep" of the group. The reason: in earlier high-pressure experiments, nitrogen showed no structures similar to those the heavier elements of this group - especially phosphorus, arsenic, and antimony - exhibit under normal conditions. Instead, exactly this kind of similarities could be observed at high pressures in the neighbouring groups headed by carbon and oxygen.

Black nitrogen - a high-pressure material with technologically attractive properties

In fact, nitrogen is no exception after all. Researchers at the Bavarian Research Institute of Experimental Geochemistry & Geophysics (BGI) and the Laboratory for Crystallography at the University of Bayreuth have now been able to prove this with the help of a measuring method they recently developed. Under the leadership of Dr. Dominique Laniel, they have made an unusual discovery. At very high pressures and temperatures, nitrogen atoms form a crystalline structure that is characteristic of black phosphorus, which is a particular variant of phosphorus. It also occurs in arsenic and antimony. This structure is composed of two-dimensional layers in which nitrogen atoms are cross-linked in a uniform zigzag pattern. In terms of their conductive properties, these 2D layers are similar to graphene, which shows great promise as a material for high-tech applications. Therefore, black phosphorus is currently being studied for its potential as a material for highly efficient transistors, semiconductors, and other electronic components in the future.

The Bayreuth researchers are proposing an analogous name for the allotrope of nitrogen they have discovered: black nitrogen. Some technologically attractive properties, in particular its directional dependence (anisotropy), are even more pronounced than in black phosphorus. However, black nitrogen can only exist thanks to the exceptional pressure and temperature conditions under which it is produced in the laboratory. Under normal conditions it dissolves immediately. "Because of this instability, industrial applications are currently not feasible. Nevertheless, nitrogen remains a highly interesting element in materials research. Our study shows by way of example that high pressures and temperatures can produce material structures and properties that researchers previously did not know existed," says Laniel.

Determining structure with particle accelerators

It took truly extreme conditions to produce black nitrogen. The compression pressure was 1.4 million times the pressure of the Earth's atmosphere, and the temperature exceeded 4,000 degrees Celsius. To find out how atoms arrange themselves under these conditions, the Bayreuth scientists cooperated with the German Electron Synchrotron (DESY) in Hamburg and the Advanced Photon Source (APS) at the Argonne National Laboratory in the USA. Here, X-rays generated by particle acceleration were fired at the compressed samples. "We were surprised and intrigued by the measurement data suddenly providing us with a structure characteristic of black phosphorus. Further experiments and calculations have since confirmed this finding. This means there is no doubt about it: nitrogen is, in fact, not an exceptional element, but follows the same golden rule of the periodic table as carbon and oxygen do," says Laniel, who came to the University of Bayreuth in 2019 as an Alexander von Humboldt Foundation research fellow.
-end-
International cooperation

In addition to the German Electron Synchrotron (DESY) in Hamburg and the Advanced Photon Source (APS) in Illinois/USA, both Goethe University Frankfurt, and the international software company BIOVIA participated in the new study as research partners of the University of Bayreuth.

Research funding

The research work at the University of Bayreuth was funded by the German Research Foundation (DFG), the Federal Ministry of Education and Research (BMBF), and the Alexander von Humboldt Foundation.

Universität Bayreuth

Related Nitrogen Articles:

'Black nitrogen'
In the periodic table of elements there is one golden rule for carbon, oxygen, and other light elements.
A deep dive into better understanding nitrogen impacts
This special issue presents a selection of 13 papers that advance our understanding of cascading consequences of reactive nitrogen species along their emission, transport, deposition, and the impacts in the atmosphere.
How does an increase in nitrogen application affect grasslands?
The 'PaNDiv' experiment, established by researchers of the University of Bern on a 3000 m2 field site, is the largest biodiversity-ecosystem functioning experiment in Switzerland and aims to better understand how increases in nitrogen affect grasslands.
Reducing reliance on nitrogen fertilizers with biological nitrogen fixation
Crop yields have increased substantially over the past decades, occurring alongside the increasing use of nitrogen fertilizer.
Flushing nitrogen from seawater-based toilets
With about half the world's population living close to the coast, using seawater to flush toilets could be possible with a salt-tolerant bacterium.
We must wake up to devastating impact of nitrogen, say scientists
More than 150 top international scientists are calling on the world to take urgent action on nitrogen pollution, to tackle the widespread harm it is causing to humans, wildlife and the planet.
How nitrogen-fixing bacteria sense iron
New research reveals how nitrogen-fixing bacteria sense iron - an essential but deadly micronutrient.
Corals take control of nitrogen recycling
Corals use sugar from their symbiotic algal partners to control them by recycling nitrogen from their own ammonium waste.
Foraging for nitrogen
As sessile organisms, plants rely on their ability to adapt the development and growth of their roots in response to changing nutrient conditions.
Inert nitrogen forced to react with itself
Direct coupling of two molecules of nitrogen: chemists from Würzburg and Frankfurt have achieved what was thought to be impossible.
More Nitrogen News and Nitrogen Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Our Relationship With Water
We need water to live. But with rising seas and so many lacking clean water – water is in crisis and so are we. This hour, TED speakers explore ideas around restoring our relationship with water. Guests on the show include legal scholar Kelsey Leonard, artist LaToya Ruby Frazier, and community organizer Colette Pichon Battle.
Now Playing: Science for the People

#568 Poker Face Psychology
Anyone who's seen pop culture depictions of poker might think statistics and math is the only way to get ahead. But no, there's psychology too. Author Maria Konnikova took her Ph.D. in psychology to the poker table, and turned out to be good. So good, she went pro in poker, and learned all about her own biases on the way. We're talking about her new book "The Biggest Bluff: How I Learned to Pay Attention, Master Myself, and Win".
Now Playing: Radiolab

Uncounted
First things first: our very own Latif Nasser has an exciting new show on Netflix. He talks to Jad about the hidden forces of the world that connect us all. Then, with an eye on the upcoming election, we take a look back: at two pieces from More Perfect Season 3 about Constitutional amendments that determine who gets to vote. Former Radiolab producer Julia Longoria takes us to Washington, D.C. The capital is at the heart of our democracy, but it's not a state, and it wasn't until the 23rd Amendment that its people got the right to vote for president. But that still left DC without full representation in Congress; D.C. sends a "non-voting delegate" to the House. Julia profiles that delegate, Congresswoman Eleanor Holmes Norton, and her unique approach to fighting for power in a virtually powerless role. Second, Radiolab producer Sarah Qari looks at a current fight to lower the US voting age to 16 that harkens back to the fight for the 26th Amendment in the 1960s. Eighteen-year-olds at the time argued that if they were old enough to be drafted to fight in the War, they were old enough to have a voice in our democracy. But what about today, when even younger Americans are finding themselves at the center of national political debates? Does it mean we should lower the voting age even further? This episode was reported and produced by Julia Longoria and Sarah Qari. Check out Latif Nasser's new Netflix show Connected here. Support Radiolab today at Radiolab.org/donate.