Skoltech has discovered an easy method to produce materials for nuclear energy and lithium-ion batteries.

The results have been published in the Journal of Alloys and Compounds. High-entropy compounds consist of four or more different principal elements, in this case — metals and carbon. In this study, the researchers synthesized titanium, zirconium, niobium, hafnium, tantalum carbide (TiZrNbHfTaC₅), as well as carbonitride from these components using a new technology. The authors note that this substance is one of the most suitable materials for manufacturing ultra-high-temperature ceramic components due to its excellent mechanical properties and thermal stability. However, the synthesis of carbide is very labor-intensive: it requires careful preparation of the raw materials and is conducted at ultra-high temperatures — around 2200-2300°C — for an extended period.

“Multicomponent and high-entropy materials have been studied relatively recently. My colleagues and I modeled various carbonitride structures with different concentrations of nitrogen and carbon and investigated their thermodynamic stability at different temperatures. We found that a high amount of nitrogen could lead to significant mechanical stresses in the lattice, which negatively impacts the material's stability,” said the head of the research, Professor Alexander Kvashnin from the Skoltech Energy Transition Project Center.

To synthesize the carbide and carbonitride, the group of scientists employed the method of plasma dynamic synthesis. This method involves using a high-speed plasma jet from an arc discharge as a medium for carrying out high-energy plasma-chemical synthesis reactions. The arc discharge and subsequent plasma flow are generated by a coaxial magnetoplasma accelerator.

“The work discusses the use of a unique scientific setup — a coaxial magnetoplasma accelerator. During an impulse of less than one millisecond, a high-speed plasma jet is formed, achieving elevated temperatures, pressure, and crystallization rates necessary for obtaining unique nanomaterials.

Together with colleagues from Skoltech, based on methods of computational material design, we were able to experimentally combine Ti, Zr, Nb, Hf, Ta, C, and N into a single structure. The method does not require special procedures for preparing raw materials, is low in energy consumption, and is universal, enabling the synthesis of various classes of materials: carbides, nitrides, oxides, carbon nanostructures, and composites based on them,” commented the first author of the study, Associate Professor Dmitry Nikitin from TPU.

The application of the plasma dynamic method for synthesizing high-entropy carbides and carbonitrides results in the production of high-quality monophasic powders. This method not only allows for the efficient production of pure high-entropy carbide TiZrNbHfTaC₅ in a dispersed monocrystalline form but also facilitates the incorporation of nitrogen into the crystal lattice, thereby synthesizing structures close to carbonitride. By using a carbon-free precursor mixture in a nitrogen atmosphere, materials containing up to eight weight percent nitrogen can be obtained.