STRUCTURAL, ELECTRONIC AND ELASTIC PROPERTIES OF TERNARY ALLOY CoxNi1-xSi2

Abstract

First-principles calculations, by means of the full-potential linearized augmented plane wave (FP-LAPW) method using the generalized gradient approximation (GGA), were carried out for the structural, electronic and elastic properties of transition metals disilicides alloy Co x Ni 1-x Si 2 in the fluorite structure. The composition effect on lattice constants and bulk modulus has been analyzed. The deviations of the lattice constants from Vegard's law and the bulk modulus from linear concentration dependence (LCD) were observed for Co x Ni 1-x Si 2. We also calculated the densities of states for the distorted Co x Ni 1-x Si 2 alloys as well as for the ordered phases CoSi 2 and NiSi 2. Theoretical values of Young's modulus, shear modulus, Poisson's ratio and Debye temperature are estimated from the computed elastic constants. The analysis of the ratio of shear modulus to bulk modulus shows that the alloy is more brittle than the binary compounds. The calculated results are compared with other reported values.