Thermodynamic modelling of the general NiAs-type structure: A study of first principle energies of formation for binary Ni-containing B8 compounds

Abstract Energies of formation of binary Ni-containing compounds with NiAs (B8)-type structure were calculated using ab-initio density functional theory. Structural relaxations and calculation of the total energies of the binary structures NiX₂ as CdI₂-type structure, NiX as NiAs-type structure and Ni₂X as Ni₂In-type structure (with X= Al, Ga, In, Si, Ge, Sn, As, Sb, Bi, Se, Te) were done using the projector augmented wave (PAW) method with a generalised gradient approximation (GGA). Overall, the calculated values are in good agreement with comparable experimental literature data. General trends of the lattice parameters and the energies of formation are discussed in detail. Nearly all of the calculated compounds are thermodynamically stable compared to the elements at zero Kelvin, although not all of them are present in the equilibrium phase diagrams. According to a recent investigation of the system Ni-Sn-Te, continuous solid solutions from CdI₂-type, over NiAs-type, up to Ni₂In-type regions are possible. Hence, a modified sublattice model according to the compound energy formalism within Calphad is proposed to give this possibility consideration. The use of the calculated energies of formation at 0 K as endmember energies within this model is discussed.