We investigate the elastic and thermodynamic properties of nanolaminate V2 AlC by using the ab initio pseudopotential total energy method. The axial compressibility shows that the c axis is always stiffer than a axis. The elastic constants revealed the structural instability at about 500 and 732 GPa. Furthermore, elastic constants C44 reached its maximum at about 550 GPa, differing with the other four C11 , C12 , C13 and C33 constants. The Poisson's ratio investigations demonstrated that a higher ionic or weaker covalent contribution in intra-atomic bonding and the degree of ionicity increases with pressure. The G/B and B/C44 investigations revealed that V2 AlC is brittle and the brittleness decreases with pressure. Also, we found that V2 AlC is elastic anisotropic materials and the degree of anisotropy rapidly rises with pressure. Study on Debye temperature and Grüneisen parameter observed weak temperature and strong pressure responses, whereas the sensitive dependence in the thermal expansion coefficient and Helmholtz free energy are clearly seen.
YANG ZeJinLIU QiangLI JinWANG ZhaoGUO AiMinLINGHU RongFengCHENG XinLuYANG XiangDong
