High-pressure nitride materials: towards the controllable and scalable synthesis in a diamond anvil cell

Project Information

HIPMAT

Grant agreement ID: 101077963

DOI

10.3030/101077963

EC signature date 15 March 2023

Start date 1 October 2023

End date 30 September 2028

Funded under

• European Research Council (ERC)

Total cost

€ 1 878 908,00

EU contribution

€ 1 878 908,00

Coordinated by

JOHANN WOLFGANG GOETHE-UNIVERSITAET FRANKFURT AM MAIN
Germany

Periodic Reporting for period 1 - HIPMAT (High-pressure nitride materials: towards the controllable and scalable synthesis in a diamond anvil cell)

Reporting period: 2023-10-01 to 2026-03-31

Summary of the context and overall objectives of the project

Modern technology increasingly depends on advanced functional materials, from high-performance semiconductors to ultrahard protective coatings.
Nitrogen-rich nitride materials may offer exceptional mechanical, electronic or magnetic properties, however, their use is often limited by current synthesis capabilities due to the thermodynamic stability and low reactivity of molecular nitrogen.
High-pressure techniques such as the diamond anvil cell (DAC) provide access to chemical spaces unreachable under ambient conditions, enabling the formation of nitrogen-rich compounds with unusual bonding motifs and novel stoichiometries.
Recent developments in laser-heating DACs and micro-analytical methods (e.g. multigrain X-ray diffraction) allow these compounds to be synthesized, studied, and recovered to ambient pressure.
Project HIPMAT focuses on three major bottlenecks of high-pressure chemical synthesis:
1. Lack of understanding of mechanisms of chemical reactions: Most high-pressure reactions are optimized blindly, without knowledge of intermediates or rate-limiting reaction steps.
2. Poor reaction control / phase purity due to inhomogeneous reaction conditions in DACs.
3. Limited sample volumes: yields remain far below what is required for device testing or technological applications.
The overall objective of the project is to design and demonstrate controllable, informed pathways to functional nitrides and to establish routes for scaling their synthesis while preserving structural and chemical integrity.
This objective will be achieved through four scientifically interconnected work packages:
WP1: Identification of synthesis conditions for targeted ternary nitrides,
WP2: Studies of mechanisms of high-pressure chemical reactions using ultrafast X-ray diffraction,
WP3: Development of reactive single-source precursors,
WP4: Synthesis upscaling in new large-volume DAC platforms.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the reporting period, the project concentrated on working packages 1 and 2, namely:
(1) establishing synthesis routes to ternary high-pressure nitride materials, and
(2) uncovering mechanisms of nitride formation via ultrafast X-ray diffraction experiments.

A broad experimental campaign was conducted across ~15 different ternary and quatenary nitrogen-rich systems to test various synthetic strategies including:
a) Azide-mediated high-pressure oxidation,
b) Two-stage high-pressure synthesis with variation of reagents between stages,
c) Single-source precursor decomposition.

Within this working package we have produced more than 20 novel compounds and identified the most efficient routes to ternary nitride perovskites through a two-stage high-pressure synthesis. In parallel, several unexpected high-pressure reaction pathways were uncovered.
For example, reactions involving trace oxides or carbon originating from diamond anvils led to a new class of high-pressure oxides, nitridocarbonates or carbides, demonstrating that careful analysis of impurities can expand chemical discovery in extreme environments.

The goal of WP2 is to investigate the kinetics and mechanisms of high-pressure chemical reactions using time-resolved X-ray diffraction at the European X-ray Free Electron Laser (EuXFEL) facility.
We studied nitride formation in three regimes: direct metal–nitrogen reactions, decomposition of single-source precursors, and reactions of metals with solid nitrogen sources.
The Fe–N system was selected as the initial test case because both pure iron and its nitrides have been extensively studied under extreme conditions, with a wealth of experimental and theoretical data available. However, the mechanisms governing their formation remain poorly understood.
Our studies revealed, for the first time, real-time phase evolution during nitrogen uptake in Fe, via a distinct transformation pathway: Fe / N2 → Fe3N → Fe2N → B8-FeN → cubic FeN. These insights provides a foundation for future rational synthesis of nitrogen-rich nitrides under extreme conditions.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

• Methodological development of multigrain X-ray diffraction enabling phase analysis of complex mixtures.
• We have developed a methodology, which includes double-stage high-pressure synthesis. Unique precursors obtained in a synthesis in large volume press can further be used for post-synthetic modification in diamond anvil cells.
• Tracking high-pressure chemical reactions in-situ at EuXFEL.
• Stabilization of uncommon metastable compounds via ultrafast X-ray or laser heating.
• Discovery of unexpected chemical compounds (novel nitridocarbonates, nitride perovskites, uncommon oxide-peroxides and others).