Mechanical properties of technetium carbides

Abstract

The mechanical properties and their electronic origins for technetium carbides have been investigated using first-principles calculations on the basis of density functional theory. The two hexagonal phases are found to have very high bulk modulus and Vickers hardness, making them ultra-low compressible and hard materials. In addition, both exhibit metallic features. The results indicate that their electronic structures are dominated by a strong hybridisation between the non-metal C-2p and metal Tc-4d states, which demonstrates strongly covalent characteristics. These directionally covalent bonds, as well as high valence electron concentration, give rise to low compressibility and high hardness. Therefore, a combination of high hardness, intense stiffness and good conductivity suggests that technetium carbides could find particular applications under extreme conditions of high temperature and pressure.

Keywords:

• Low compressibility
• High hardness
• Electronic structures
• Technetium carbides
• First-principles calculations