Knight Shift in Silver Base Solid Solutions

This paper describes an experimental investigation of some primary substitutional solid solutions of silver. Nuclear magnetic resonance was used to detect the charge density at the solvent nuclei in these alloys, and the results are compared with theory. Solutes chosen for the study were Cu, Zn, Ga, Ge, As, Cd, In, Sn, Sb, Au, and Tl. Insertion of a few percent of any of these caused a decrease in the Knight shift of silver in rough proportion to both solute concentration and valence. Also the normally narrow silver absorption became very broad under the influence of a few percent solute. This severe broadening serves as the major basis for an argument concerning the distribution of charge density around the solute atoms. It is shown that dipolar and indirect exchange broadening are not sufficient to account for the observed line-widths; subsequently the absorption is analyzed in terms of the long-range oscillations in the conduction electron density thought to be present in the vicinity of the solute atoms. The comparison with theory indicates that the line shift and width are equally well explained by the presence of long-range oscillations. If the shift were much greater than that observed it would suggest another source of shift not included by the present mechanism. It is concluded that the theory of Blandin, Daniel, and Friedel is applicable to these alloys and explains the data satisfactorily. It is not possible to test the theory quantitatively unless one knows the exact phase shifts to describe the scattering process underlying this theory.