A first-principles comparison of the electronic properties of MgC_{y}Ni_{3} and ZnC_{y}Ni_{3} alloys

TL;DR

This study uses first-principles calculations to compare the electronic and phononic properties of ZnC_{y}Ni_{3} and MgC_{y}Ni_{3} alloys, revealing differences in their lattice, bulk modulus, and phonon spectra related to composition.

Contribution

It provides a detailed first-principles comparison of the electronic structure and phonon-related properties of ZnC_{y}Ni_{3} and MgC_{y}Ni_{3} alloys, highlighting differences due to compositional changes.

Findings

Lattice constant and bulk modulus decrease with decreasing C at% in both alloys.

ZnCNi_{3} and its alloys have different phonon spectra compared to MgCNi_{3}.

Electronic structure similarities suggest comparable density of states at the Fermi level.

Abstract

First-principles, density-functional-based electronic structure calculations are employed to study the changes in the electronic properties of ZnC_{y}Ni_{3} and MgC_{y}Ni_{3} using the Korringa-Kohn-Rostoker coherent-potential approximation method in the atomic sphere approximation (KKR-ASA CPA). As a function of decreasing C at%, we find a steady decrease in the lattice constant and bulk modulus in either alloys. However, the pressure derivative of the bulk modulus displays an opposite trend. Following the Debye model, which relates the pressure derivative of the bulk modulus with the average phonon frequency of the crystal, it can thus be argued that ZnCNi_{3} and its disordered alloys posses a different phonon spectra in comparison to its MgCNi_{3} counterparts. This is further justified by the marked similarity we find in the electronic structure properties such as the variation in the density of states and the Hopfield parameters calculated for these alloys. The effects on the equation of state parameters and the density of states at the Fermi energy, for partial replacement of Mg by Zn are also discussed.