Positron annihilation studies on the electronic structure of Ni1-xCuxalloys

The entire concentration range of α-phase Ni 1- x Cu x alloys has been studied by Angular Correlation and Positron Lifetime methods. The results show inapplicability of the Rigid Band Model to description of the electronic structure of this alloy. Linearity of annihilation rate λ( x ) as well as of parameters of correlation curves leading to linearity of s-like and d-like electron numbers with x confirms our earlier expectation as to the character of annihilation parameters for split-band alloys with constant Fermi energy. On the ground of the present results and the previous ones for palladium alloys it was postulated that the behaviour of the bulk annihilation rate in binary alloys can predict which type of the electronic structure, split-band or VCA, is the appropriate one in the given case.