<i>Ab Initio</i> Study of the Structural and Mechanical Properties of Hf-Si-N

Abstract

The structural and elastic properties of HfN and Hf-Si-N have been studied, using first principles calculations based on the density functional theory. These calculations provide the lattice parameter, cohesive energy and elastic constants of fcc (NaCl)-HfN, the N-deficient Hf-Si-N and the Hf-deficient Hf-Si-N solution phase. In order to study the relative stability, binding energy of all configurations has been calculated. The results showed that it was difficult to add a Si atom into the center of the HfN cell because the cohesive energy decreased. However, if an Hf atom or an N atom was missing in the HfN, a silicon atom was possible to occupy the vacant site and form the Hf-Si-N substitutional solid solution. Moreover, the bulk modulus, shear modulus and elastic modulus increased accordingly, the mechanical properties were improved.

Preparation and high‐temperature behavior of HfC–SiC nanocomposites derived from a non‐oxygen single‐source‐precursor

“…Hf, C and Si appear at the boundaries of the HfC and SiC grains at high temperature . A silicon atom is possible to occupy the vacant site and form the Hf–Si–N substitutional solid solution . As the covalent radius of carbon (R C =0.75 Å) is comparable to that of nitrogen (R N =0.71 Å) and the crystal structure of HfC is same as that of HfN with NaCl F‐type crystal structure, it is reliable that solid solution Hf–Si–C has very similar properties with Hf–Si–N.…”