High-pressure Nitrides and Hydrides

My research aims at understanding structural, electronic and dynamical properties of hydrides and nitrides with promising functionalities at high-pressure and finding ways to preserve their stability and properties to ambient conditions.

In order to understand underlaying mechanisms leading to structureal stability and functionalities at a given pressure and temperature condition, I use density-functional-theory based computations in collaboration with experimental colleagues employing nuclear magnetic resonance (NMR) and X-ray diffraction (XRD) experiments.

Find my list of publications and preprints on Google Scholar.

Recent Research Projects

Hydrogen-bearing compounds: hydrous minerals & metal hydrides

Direct hydrogen quantification in high-pressure metal hydrides.

Thomas Meier, Dominique Laniel & Florian Trybel (2023). Matter and Radiation at Extremes, 8(1), 018401. 

Severe limitations in determining the chemical formula of metal hydrides synthesised at extreme conditions, especially with regards to their hydrogen content, impedes a deep understanding of the realised phases and can lead to significantly erroneous conclusions. We found a way to access the hydrogen content of metal hydride solids synthesized at high pressures in (laser-heated) diamond anvil cells directly in-situ at high pressure using nuclear magnetic resonance spectroscopy.A schematic figure of hydrogen-quantification Photo credit Thomas Meier

Structural independence of hydrogen-bond symmetrisation dynamics at extreme pressure conditions.

Thomas Meier, Florian Trybel, et al. (2022). Nature Communications

The experimental study of hydrogen-bonds and their symmetrization under extreme conditions is predominantly driven by diffraction methods, despite challenges of localising or probing the hydrogen subsystems directly. Until recently, Schematics of Hydrogen-bond-symmetrisation H-bond symmetrization has been addressed in terms of either nuclear quantum effects, spin crossovers or direct structural transitions; often leading to contradictory interpretations when combined. Here, we present high-resolution in-situ 1H-NMR experiments in diamond anvil cells investigating a range of systems containing linear O-H O units at pressure ranges of up to 90 GPa covering their respective H-bond symmetrization. We found pronounced minima in the pressure dependence of the NMR resonance line-widths -- independent of the chemical environment of the O-H O unit -- at an average critical oxygen-oxygen distance of 2.44 to 2.45 Å.

Press release: Universal Transitions in Hydrogen Bonds under Extreme Conditions 

Press release: In Nature Communications: New spectroscopic insights into hydrogen bonds 

High-pressure synthesis of seven lanthanum hydrides with a significant variability of hydrogen content

Dominique Laniel, Florian Trybel, et al. (2022). Nature communications

The lanthanum-hydrogen system has attracted significant attention following the report of superconductivity in LaH10 at near-ambient temperatures and high pressures. Phases other than LaH10 are suspected to be synthesized based on both powder X-ray diffraction and resistivity data, although they have not yet been identified. We present the results of our single-crystal X-ray diffraction studies and DFT calculations on this system, which reveal an unexpected chemical and structural diversity of synthesised lanthanum hydrides.

Press release: Progress towards hydrogen-based solid superconductivity

Press release: Leading the way in superconductor research: new compounds of lanthanum and hydrogen

Proton dynamics in high-pressure ice-VII from density functional theory.

Schematic figure over proton dynamics in high-pressure ice-VII

Florian Trybel, et al. (2020). Physical Review B 102, 184310

Using a density-functional-theory-based approach, we explore the symmetrisation and proton dynamics in the high pressure H2O ice-VII phase, for which recent high-pressure NMR experiments indicate significant proton dynamics in the pressure-range of 20– 95 GPa. We directly sample the potential seen by the proton and find a continuous transition from double- to single-well character over the pressure range of 2 to 130 GPa accompanied by proton dynamics, in agreement with NMR experiments.

Pressure induced Hydrogen-Hydrogen interaction in metallic FeH revealed by NMR. 

Thomas Meier, Florian Trybel, et al. (2019). Physical Review X, 9, 031008 (2019)

Knowledge of the behaviour of hydrogen in metal hydrides is the key for understanding their electronic properties. Performing high-pressure 1H-NMR and density-functional theory-based calculations on cubic FeH up to 202 GPa, we observe a distinct deviation from ideal metallic behaviour between 64 and 110 GPa that suggests the emergence of pressure-induced H-H interactions. Ab-initio calculations reveal the formation of an intercalating sub-lattice of electron density, which enhances the hydrogen contribution to the electronic density of states at the Fermi level. This study shows that pressure-induced H-H interactions can occur in metal hydrides at much lower compression and larger H-H distances than previously thought.

Press release: First Observation of Hydrogen-Hydrogen Interactions in Metal Hydrides at Multi-Megabar Pressures 

Schematics of pressure induced Hydrogen-Hydrogen interaction


Understanding the stability and properties of hydrous minerals, possibly contributing to hydrogen transport to the lower mantle is crucial as key properties of the constituents of Earth’s mantle, e.g., melting temperatures, rheology, electrical conductivity and atomic diffusivity can be strongly affected by the presence of even small amounts of hydrogen.

Hydrides synthesised at extreme conditions show furthermore promising functionalities for hydrogen storage and room-T superconductivity. However, a reliable analysis of hydrogen-bearing phases at extreme conditions purely from experiment is often not possible and even in combination with computations it is not straightforward to unambiguously refine structures or understand properties.

Therefore, I am working with a broad range of collaborators on finding new techniques and new synergies between experiment and theory, especially the combination of high-pressure NMR with density-functional-theory-based calculations, in order to improve our understanding of phase stability, properties and functionalities of these phases.


Aromatic hexazine [N₆]⁴⁻ anion featured in complex structure of the high-pressure potassium nitrogen compound K₉N₅₆. 

Dominique Laniel, Florian Trybel, et al.: Nature Chemistry (2023) 

Schematics of Aromatic hexazine [N₆]⁴⁻ anion featured in  complex structure of the high-pressure potassium nitrogen compound K₉N₅₆. We present the first synthesis of a compound featuring aromatic nitrogen 6-rings. The hexazine anion [N6]4− was realised in the high-pressure potassium nitrogen compound K9N56 formed at P > 60 GPa and temperatures > 2000 K. The complex structure of K9N56—composed of 520 atoms per unit cell—was solved based on synchrotron single-crystal X-ray diffraction and corroborated by density functional theory calculations. The observed hexazine anion [N6]4− is planar and proposed to be aromatic.

Press release: First synthesis of a compound with aromatic nitrogen rings

Press release: Synthesis and characterization of a new nitrogen aromatic species

Revealing Phosphorus Nitrides up to the Megabar Regime: Synthesis of α′‐P3N5, δ‐P3N5 and PN2. 

Dominique Laniel, Florian Trybel, et al. (2022). Chemistry–A European Journal, 28(62), e202201998.

We studied the phosphorus–nitrogen system at up to 137 GPa in laser-heated diamond anvil cells. Three previously unobserved phases were synthesized and characterized by single-crystal X-ray diffraction, Raman spectroscopy measurements and density functional theory calculations. δ-P3N5 and PN2 were found to form at 72 and 134 GPa, respectively, and both feature dense 3D networks of the so far elusive PN6 units. The two compounds are ultra-incompressible, having a bulk modulus of K0=322 GPa for δ-P3N5 and 339 GPa for PN2. Upon decompression below 7 GPa, δ-P3N5 undergoes a transformation into a novel α′-P3N5 solid, stable at ambient conditions, that has a unique structure type based on PN4 tetrahedra. The formation of α′-P3N5 underlines that a phase space otherwise inaccessible can be explored through materials formed under high pressure.

Press release: International research team creates previously unknown nitrogen compounds 

Anionic N₁₈ Macrocycles and a Polynitrogen Double Helix in Novel Yttrium Polynitrides YN₆ and Y₂N₁₁ at 100 GPa.

Andrey Aslandukov, Florian Trybel et al.: Angewandte Chemie International Edition (2022)

Schematics of Revealing Phosphorus Nitrides up to the Megabar Regime: Synthesis of α′‐P3N5, δ‐P3N5 and PN2. Photo credit Andrey Aslandukov Two novel yttrium nitrides, YN6 and Y2N11, were synthesized by direct reaction between yttrium and nitrogen at 100 GPa and 3000 K in a laser‐heated diamond anvil cell, featureing a unique organization of nitrogen atoms—a previously unknown anionic N18 macrocycle and a polynitrogen double helix, respectively. Density functional theory calculations, confirming the dynamical stability of the YN6 and Y2N11 compounds, show an anion‐driven metallicity, explaining the unusual bond orders in the polynitrogen units.

Press release: New study by the University of Bayreuth: Nitrogen forms extremely unusual structures under high pressure


Nitrides are known to exhibit outstanding mechanical and electronic properties, relevant for hard coatings, solid-state lighting, photovoltaics, thermo- and piezo-electrics as well as being green high-energy-density materials. Despite their outstanding potential, nitrogen compounds are still strikingly uncommon, as nitrogen is only weakly reactive at ambient conditions. At extreme pressures of millions of times the atmospheric pressure and under laser heating to thousands of degrees, however, nitrogen becomes significantly more reactive and forms stable compounds with a variety of elements. We explore the stability and properties of newly synthesised nitride phases together with experimental collaborators in order to find pathways towards maintaining extraordinary functional properties to ambient conditions.



Yuqing Yin, Alena Aslandukova, Nityasagar Jena, Florian Trybel, Igor Abrikosov, Bjoern Winkler, Saiana Khandarkhaeva, Timofey Fedotenko, Elena Bykova, Dominique Laniel, Maxim Bykov, Andrey Aslandukov, Fariia I. Akbar, Konstantin Glazyrin, Gaston Garbarino, Carlotta Giacobbe, Eleanor L. Bright, Zhitai Jia, Leonid Dubrovinsky, Natalia Doubrovinckaia (2023) Unraveling the Bonding Complexity of Polyhalogen Anions: High-Pressure Synthesis of Unpredicted Sodium Chlorides Na2Cl3 and Na4Cl5 and Bromide Na4Br5 JACS Au Continue to DOI
Dominique Laniel, Florian Trybel, Yuqing Yin, Timofey Fedotenko, Saiana Khandarkhaeva, Andrey Aslandukov, Georgios Aprilis, Alexei I. Abrikosov, Talha Bin Masood, Carlotta Giacobbe, Eleanor Lawrence Bright, Konstantin Glazyrin, Michael Hanfland, Jonathan Wright, Ingrid Hotz, Igor A. Abrikosov, Leonid Dubrovinsky, Natalia Doubrovinckaia (2023) Aromatic hexazine [N6]4− anion featured in the complex structure of the high-pressure potassium nitrogen compound K9N56 Nature Chemistry Continue to DOI


Dominique Laniel, Florian Trybel, Adrien Néri, Yuqing Yin, Andrey Aslandukov, Timofey Fedotenko, Saiana Khandarkhaeva, Ferenc Tasnadi, Stella Chariton, Carlotta Giacobbe, Eleanor Lawrence Bright, Michael Hanfland, Vitali Prakapenka, Wolfgang Schnick, Igor A. Abrikosov, Leonid Dubrovinsky, Natalia Doubrovinckaia (2022) Front Cover: Revealing Phosphorus Nitrides up to the Megabar Regime: Synthesis of α′-P3N5, δ-P3N5 and PN2 (Chem. Eur. J. 62/2022) Chemistry - A European Journal, Vol. 28, Article e202203122 Continue to DOI
Leonid Dubrovinsky, Saiana Khandarkhaeva, Timofey Fedotenko, Dominique Laniel, Maxim Bykov, Carlotta Giacobbe, Eleanor Lawrence Bright, Pavel Sedmak, Stella Chariton, Vitali Prakapenka, Alena V. Ponomareva, Ekaterina A. Smirnova, Maxim P. Belov, Ferenc Tasnadi, Nina Shulumba, Florian Trybel, Igor A. Abrikosov, Natalia Dubrovinskaia (2022) Materials synthesis at terapascal static pressures Nature, Vol. 605, p. 274-278 Continue to DOI