First-principles calculations of structural, electronic, elastic and thermal properties of phase M2SiC (M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W)

The structural, electronic and elastic properties of the M2SiC phases were studied, where M are 3d, 4d, and 5d early transition metals. The valence electron concentration (VEC) effect of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W on these properties was examined. The C44 saturates for a VEC value in surrounding of 8.5 for each serie. Hf-s, Ta-s and W-s electrons mainly contribute to the density of states at the Fermi level, and should be involved in the conduction properties. The distortion increases with increasing VEC and decreasing kc/ka factor except for the series M=Ti, V and Cr, where it is lower at the VEC value of 8.5 (it follows a parabolic variation). The M2SiC was characterized by a profound anisotropy for the shear planes (1010) and compressibility in the direction is higher than that along the cone except for W2SiC, where it is lower.