Book/Report

FZJ-2018-01862

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Vermessung der Fermiflächen von Kupfer-Mischkristallen

Steinmetz, K.-H. (Corresponding author)FZJ*

1982
Kernforschungsanlage Jülich, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/17672

Report No.: Juel-1773

Abstract: Fermi-surfaces (FS) of binary Cu-alloys (Cu-Ga, Cu-Ge and Cu-Ni) are investigated by use of the method of positron annihilation. Especially the dependence of the neck-radii of the FS on the alloy-concentration is examined. The "rotating-specimen-method" is used with a constant deviation-angle ($\theta$ = O$^{o}$) combined with a "crossed-slit-geometry", which yields a resolution of 0,9 x 1,7 mrad$^{2}$. To improve the intensity, up to 72 collimators are used simultanously in anspecial "sandwich" arrangement. Hume-Rotherys and Jones' model, which exclusively links the stability of phases to the valence of the constituent atoms, implies that the electronic structure of alloys is independent of the specific solutes, which means that the dimensions of the FS of Cu-base solid solutions, namely the radius of the <111>-neck(K$_{N}$) is an unique, monotonuous function of the electron per atom ratio, e/a. This is at variance with the present measurements. In the case of Cu-Ga and Cu-Ge, K$_{N}$ increases upon alloying, i.e. with increasing e/a. In this regard qualitative agreement is obtained with Jones' model. But for a given increaseof e/a, Ga widens the neck of the FS about 30 % more than Ge does, though the maximum solubilities are at nearly identical e/a-ratios. In the case of Cu-Ni the present measurements show, that the neck-radius of the FS doesn't decrease with increasing Ni-concentration, in the contrary K$_{N}$ (Cu - 22 at % Ni) is about 18 % larger than K$_{N}$ (Cu). This is attributed to the fact, that Ni modifies the density of electron states. The effect of the Ni 3d-states have to be taken into consideration.

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Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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