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

• Energies of formation of compounds with NiAs (B8)-type structure were calculated.
• Binary structures Ni-X with X= Al, Ga, In, Si, Ge, Sn, As, Sb, Bi, Se, Te.
• NiX2 as CdI2-type, NiX as NiAs-type and Ni2X as Ni2In-type structure.
• General trends of lattice parameters and energies of formation are discussed.
• A modified sublattice model for the general NiAs-type structure is proposed

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.

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