Theoretical study of structural, electronic and lattice dynamical properties of novel AlNiP half-Heusler alloy.

In this work, the structural, electronic, and dynamical properties of novel half-Heusler (HH) alloy AlNiP are studied by applying first-principles density functional theory (DFT). The structural properties of AlNiP in the LiAlSi-type crystal structure with three different phases (α-phase, β-phase, and γ-phase) in different atomic arrangements are explored. The 'γ-phase' of AlNiP is found to be energetically stable among three. Moreover, the calculated ferromagnetic (FM), non-magnetic (NM) and anti-ferromagnetic (AFM) state for AlNiP favours the 'NM' state. The overlapping of the valence band and conduction band signifies the metallic characteristics of the alloy at 0 GPa and high pressure 38 GPa. The lattice dynamics of novel HH alloy AlNiP have also been investigated by applying DFT followed by density functional perturbation theory (DFPT). The phonon calculation suggests the face-centred cubic phase of HH alloy AlNiP is stable at ambient condition and also at high pressure of 38 GPa. For the confirmation of this stability, the phonon density of states has also been calculated at zero and higher value of pressure. The calculated results are further interpreted in the light of the similar type of alloys. [ABSTRACT FROM AUTHOR]