University of Bayreuth, Press Release No 147/2023 - 12 October 2023

Bayreuth Scientists Unlock the Secrets of Nitrogen’s Solid Phase

In a ground-breaking study led by the University of Bayreuth researchers, in collaboration with scientists from the University of Edinburgh, UK, and the University of Linköping, Sweden, the mysteries of nitrogen’s solid phases were solved, shedding light on its complex behaviour. Their findings, published in the journal Nature Communications, provide unprecedented insights into the gradual molecular-to-polymeric transformation of nitrogen and the formation of amorphous nitrogen. This paves the way for advances in materials science and high-pressure physics

Prof. Leonid Dubrovinsky and Prof. Natalia Dubrovinskaia discussing the modell of nitrogen molecules built of nitrogen atoms in none-equivalent crystallographic positions discovered in novel high-pressure solid nitrogen allotrope. 

The implications of this research extend beyond nitrogen itself, offering a deeper understanding of molecular transformations under extreme conditions. The findings pave the way for advancements in solid-state sciences, materials science and high-pressure physics. The researchers improve the methods of studying the properties of functional materials used in electronics, computer chips, semiconductors, solar cells, batteries, lighting, metals or insulators.

At ambient pressure and temperature, nitrogen is gas and is found in the form of an N₂ molecule (N≡N) composed of an extremely strong triple-bond. When extreme pressures are applied to molecular gaseous nitrogen, it first becomes liquid and then a solid at about 2.5 GPa (i.e. 25,000 times the atmospheric pressure). For over a century, scientists have delved into solid phases of molecular nitrogen, asnowledge of the chemico-physical mechanisms underpinning transformations in nitrogen is vital in testing and refining theories of solid-state sciences.

 The Zeta-N₂phase of nitrogen, existing between 60 and 115 GPa, is a critical piece of the puzzle for understanding nitrogen’s molecular to polymeric transition. However, despite a large number of investigations, its crystal structure (i.e. the nitrogen molecules’ arrangement) was hitherto unknown—and key to deciphering nitrogen’s odd behaviour. The research team, led by Dominique Laniel (University of Edinburgh) and Natalia Dubrovinskaia and Leonid Dubrovinsky (the University of Bayreuth) employed an experimental technique newly developed in Bayreuth to successfully determine the crystal structure of Zeta-N2. The researchers squeezed molecular nitrogen in diamond anvil cells to extreme pressures between 60 and 85 GPa, such as those prevailing in the Earth's mantle. By applying laser heating up to 2000 degrees Celsius, they were able to recrystallize high-quality submicrometer-size grains of Zeta-N₂. Their crystal structure (see Figure) was solved and refined from synchrotron single-crystal X-ray diffraction. With these experimental findings in hand, theoreticians at the University of Linköping (Sweden) gained further insights into nitrogen’s unique polymerization process.

The crystal structure of the Zeta-N₂ phase of molecular nitrogen.

Laniel, D., Trybel, F., Aslandukov, A. et al. Title: Structure determination of ζ-N2 from single-crystal X-ray diffraction and theoretical suggestion for the formation of amorphous nitrogen. Nat Commun 14, 6207 (2023). 

Prof. Dr. Natalia Dubrovinskaia

Prof. Dr. Dr. h.c. Natalia Dubrovinskaia

Laboratory for Crystallography
University of Bayreuth

Phone: +49 (0)921 / 55-3880 or -3881

Profil von Prof. Dr. Leonid Dubrovinsky

Prof. Dr. Dr. h.c. Leonid Dubrovinsky

Bavarian Research Institute of Experimental Geochemistry & Geophysics (BGI)
University of Bayreuth

Phone: +49 (0)921 / 55-3736 or -3707

Portraitbild von Anja Maria Meister

Anja-Maria Meister

PR Spokesperson University of Bayreuth

Phone: +49 (0) 921  55 - 5300