Effect of Ternary Additions X (Co, Rh, Ir) on Electronic Properties of TiPd Shape Memory Alloy: An ab-initio Study

Abstract

The structural and electronic properties of TiPd-X (X = Co, Rh, Ir) alloys are studied using first principles calculations. The site preference of X impurities in TiPd is determined from the calculated formation energy. It is found that ternary additions X prefer Ti sublattice more than Pd sublattice for the composition considered. The densities of states (total, site and angular momentum decomposed) are plotted for both Ti 43.75 Pd 50 X 6.25 and Ti 50 Pd 43.75 X 6.25 series. The density of Ti d-states and localization effect of ternary additions at the Fermi level determines the phase stability of these compounds. Band structure calculations are consistent with the results of density of states. Fermi surface topology of Ti 43.75 Pd 50 Co 6.25 and Ti 43.75 Pd 50 Ir 6.25 are studied in detail. The electron density contour maps give a picture of the bonding situation in these alloys.