Effects of Vacancies on the Structural, Elastic, Electronic and Thermodynamic Properties of C11b-VSi2 by First-Principles Calculations

Abstract

The effects of V and Si vacancies on structural stability, elastic properties, brittleness-toughness transition, Debye temperature and electronic properties of tetragonal C11b-VSi2 are investigated using the first-principles calculations. The vacancy formation energy and phonon dispersions confirm that perfect C11b-VSi2 and C11b-VSi2 with different atomic vacancies are thermodynamically and dynamically stable. The C11b-VSi2 with V-atom vacancies is more stable than that with Si-atom vacancies. The introduction of different atomic vacancies enhances the elastic modulus and its anisotropy of C11b-VSi2. The electron density difference and densities of state of perfect VSi2 and VSi2 with different vacancies are calculated, and the chemical bonding properties of perfect VSi2 and VSi2 with vacancies are discussed and analyzed. Additionally, the results show that the chemical bond strength of VSi2 is enhanced by the introduction of vacancies. Finally, Debye temperatures of perfect VSi2 and VSi2 with vacancies are also calculated.