Atomistic structure and morphology of nanocrystalline niobium carbide obtained by electrochemical transport reactions
摘要
The strength characteristics of composite materials depend not only on their structural and phase composition, but also on the size of matrix and hardening particles in compacted materials. Therefore, maintaining a small grain size in the final material and improving the properties of the compound is an important task. This study investigates the atomistic structure of nanocrystals of nonstoichiometric niobium carbide (NbCy) synthesized using directed spontaneous transfer of metal ions in molten salts without electric current. The obtained powder was studied using X‑ray diffraction, scanning electron microscopy, and spectral analysis with an inductively coupled plasma. According to X‑ray diffraction data, NbCy nanocrystals have a cubic structure (space group is Fm–3m); the average size of the crystallites is about 28 nm. A specific feature of the synthesized powders is the presence of hollow spheres with sizes of about 10–20 nm and 200–300 nm. The bimodal pore structure allows the resulting spheres to be filled with particles or molecules of different sizes. Such a structure can be considered as a matrix for the introduction of additional elements or gases, i.e., for the creation of composites with new properties. In addition, the obtained nanopowder is an appropriate component for creating catalysts for chemical and electrochemical reactions and materials operated under extreme conditions.