Electronic Structure of Cu-Pd Alloys

Abstract

Cu-Pd alloys containing 12.6-60.6 at% Pd, when quenched from the fee phase field are known to exhibit diffuse scattering at the 100 and the 110 positions in reciprocal lattice and these diffraction effects are believed to be characteristic of the short range order(SRO) present in these alloys[1]. Moreover, quenched fcc alloys containing more than 13 at% Pd actually exist in a state of modulated SRO, i.e., the diffuse intensity maxima at 100 and 110 reciprocal lattice positions are associated with two-fold and four-fold splitting respectively [1,2]. These effects arise as a result of accidental minima in the ordering potential, V(k) in reciprocal space located away from the special point of the fee structure [2]. Another explanation for the above diffraction effects is from the theory due to Krivoglaz [3] and Moss [4] according to which the long range oscillatory part of V(k) plays a significant role in these alloys and Pd additions increase the flat portions of the Fermi surface of Cu in the <110> directions and this is manifested in the form of strong Kohn like anomaly surfaces in reciprocal space [1,4].