Theorical investigation of structural, electronic, elastic and vibrational properties of Pd2XAl (X=Co, Fe, Ni, Ti, Cu) ve Pt2XAl (X=Co, Fe, Ni, Ti, Cu) Heusler alloys in cubic structure

In this thesis, the structural, electronic, elastic and vibrational properties of the Pd2XAl (X=Co, Fe, Ni, Ti, Cu) and Pt2XAl (X=Co, Fe, Ni, Ti, Cu) Heusler alloys in L21 structure were investigated by using the density functional theory (DFT) within the generalized gradient approximation (GGA). The structural parameters (Lattice constant, bulk moduls, presure first derivative of bulk modulus) and elastic constant were obtained. Electronic band structures and densities of states were derived for Pd2XAl (X=Co, Fe, Ni, Ti, Cu) and Pt2XAl (X=Co, Fe, Ni, Ti, Cu). The calculated total spin magnetic moments are 1,82 ?B for Pd2CoAl, 3,20 ?B for Pd2FeAl, 1,86 ?B for Pt2CoAl, 3,31 ?B for Pt2FeAl. A linear response approach to the density functional theory is used to calculate the phonon frequencies and densities of states for these Heusler allos. Phonon spectra calculations show that all materials in L21 structure are unstable dynamically.Key Words : Heusler Alloys, Electronic Band Structure, Phonon, DFT