High-pressure chemistry of nitrogen-rich compounds

• Applicant: Professor Dr. Maxim Bykov
• Subject Area: Solid State and Surface Chemistry, Material Synthesis
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 459992662

Key aspect of the material science and technology today is designing approaches for producing novel materials for sustainable development, such as environmentally friendly materials, materials for hydrogen and energy storage, lightweight and ultra-hard materials etc. Applying extreme conditions, such as high pressures and high temperatures, in chemical synthesis enables novel routes to metastable and kinetically hindered compounds. Nitrides are the class of compounds that especially benefit from the applications of pressure, which can help not only to stabilize expected classical nitrides but also to greatly enrich the chemistry of binary nitrides by promoting the formation of homonuclear N–N bonds and polynitrogen species in new atypical compounds. The practical use of these nitride compounds spans from ultrahard, incompressible materials, light-emitting diodes, ferroelectrics to high-energy density materials. However, the high-pressure solid-state chemistry faces several fundamental challenges. First one is almost complete absence of the chemical intuition for the reactions that occur at pressures above 50 GPa, that is defined by the lack of systematic empirical information. Therefore, nowadays, the high-pressure chemistry of nitrogen is dominated by the ab initio structure prediction methods, which provide very valuable information for the experimental realization of novel materials, but strongly require an independent experimental feedback. The second challenge is that the size of the sample, that could be synthesized in a conventional diamond anvil cell, does not allow studying all the properties of the material and limits any practical applications. Therefore, the development of a scalable high-pressure synthesis of novel atypical compounds is the essential step for the advancement of the high-pressure solid-state chemistry. In this project we concentrate on both challenges. First, we propose to systematically study the high-pressure chemistry of nitrogen in its reactions with alkali and alkaline-earth metals (ionic polynitrides), main-group elements (covalent polynitrides), and transition metals (mixed ionic and covalent compounds). This will build a solid basis for increasing the structural and compositional complexity in ternary and quaternary systems, as well as for the targeted synthesis of materials with desired properties (e.g. ferroelectric nitride perovskites). Secondly, we will focus on the development of scalable synthetic procedures that would allow getting access to the bulk properties of novel high-pressure materials. These technological advances will be of great importance not only for the chemistry of nitrides, but for the whole field of high-pressure solid-state chemistry.

• DFG Programme: Independent Junior Research Groups
• International Connection: Sweden
• Major Instrumentation: Double-sided laser-heating system
• Instrumentation Group: 5750 Spezielle Laser-Mess-Systeme (z.B. Laser-Doppler-Vibrometer)
• Cooperation Partner: Professor Dr. Igor Abrikosov