Crystal structure, electronic and elastic properties for novel Hf3AlN and Zr3AlN ceramics explored by first principles studies

Investigations into crystal structure, electronic and elastic properties of M3AlN (M=Hf, Zr) had been conducted by plane-wave pseudopotential calculations. The absence of band gap at the Fermi level and the finite value of the density of states at the Fermi energy reveal the metallic behavior of these two compounds. The charge density distributions and density of states indicate that there exist relatively soft Al–M and strong N–M covalent bonds, which might be contributed to layered chemical bonding character of M3AlN. By analyzing Cauchy pressure and the bulk modulus to C44 ratio, Hf3AlN was predicted to be more ductile than Zr3AlN.